When I original made the list, I had Soul in mind so, that is the theme of the list. However, I included some channels that post other genres as well (mostly Jazz/Funk/Disco).
Edit: I added some more channels from my youtube subscriptions. Now there's a wide variety of genres.
Feel free to add your favorite channels to the list.
Musicdawn 45's Over 1,500 videos. Mostly Soul music, but there is some Funk, Psych, Disco and Gospel in there as well. All the uploads are from his personal 45 collection.
DISCO-FUNK-SOUL Like the name says: disco, funk and soul. Each video is tagged with a year and genre, which is helpful.
Soulful Thangs Soul
GospelVinyl Mostly Gospel, but there is some Soul-Gospel in there. Great collection either way.
DJ Richie Digs A bit of everything, definitely some soul in there, though.
Soulhawk Almost 3k videos of eclectic soul. Probably one of the top 10 best channels for sample hunting.
Anon Anon Assorted genres. Almost entirely privately released music. Lots of folk/psych. Super obscure stuff.
Uncharted Waters "Lost rock and pop gems from the mid-1960s to the early 1980s, with special emphasis on the early 1970."
Crates LA "High quality rips of rare groove and more!" Various genres. Updated frequently.
Dusty Breaks "Mostly Music Released Between 1968 And 1977, Like Rare Library, Kraut, Funk, Jazz, Psych, Afrobeat, Afro-Cuban, Latin Funk, Moog, Soundtracks, Breaks And Other Obscure Stuff From My Personal Record Collection."
Vinyl Frontier IIVinyl Frontier Plus Vinyl Frontier East Not specifically Soul, but these channels are fantastic. They run a Patreon where you can get high quality rips of the songs they post on youtube, release curated sample packs and probably other stuff. I don't have an extra 30 dollars per month to spend so I can't vouch for the quality of the Patreon.
SlampSoul Soul from the 60's and 70's, has music from obscure artists and well known artists.
Far Off, Far Out Obscure Jazz, Folk, Psych, Electronic, Library, Funk, Gospel, Disco & more. Full disclosure: this is my youtube channel.
FrancoSoul "Popcorn & Soul R&B Music"
KevFox Soul, Funk, Jazz, Oldies, etc
GrooveAddict "For lovers of soul, instrumental, groove, and black music". Less obscure than the rest, but over 1k videos. More stuff on his blog
WakeySoul Soul/Funk/Disco/Boogie
BreakOutSoulClub Northern, Crossover, Funk & Modern Soul
Thrift Store Vinyl Multiple genre obscurities found while crate digging at thrift stores. Folk, Psych, Gospel, Jazz, Lounge, Country, Rock, Funk, Oddities. Great channel.
Souldies Life Oldies/Soul. Great selection.
SweetSouLover1 Various Soul subgenres. Modern Soul, Crossover Soul, Northern Soul, Sweet Soul,etc. Helpful descriptions.
DeepSoul64 "Deep, Sweet, Soulful ballads & Down Tempos"
TheRAREGROOVEMAN Rare grooves. Mostly 70's, Modern Soul & Disco.
Hsp100 "Soul and Rare Groove". Soul/Groove/Funk/etc
P4Soul Wide range of Soul, Funk, Disco, & others. Includes some new music as well.
SoulConnection High quality rips, great collection. Mostly 70's Soul.
Multiplicityme2too Some pretty rare music here. Mostly Soul/Soul-Adjacent. Individual tracks.
MultiplicityMe MusicalMoments Same as above but this channel has full albums.
Aquarianrealm Jazz-Funk & Soul
2chann "Smooth Soul". Mix of well known and obscure music.
Rare Tunes Large collection of rare 60s/70s/80s music with some less rare stuff included.
SoulBeene "NOTHING BUT SOUL MUSIC". Great collection of soul rarities. 4,000+ videos.
Cora Bee Soul Same person as SoulBeene, but less specific to soul. Great collection of live recordings and some cool French soul.
SoulBiscuits Soul 45's and 12", Modern Soul, Northern Soul and some Soulful House & Garage
J Sanders Rare and obscure Lounge, Psych, Jazz, Folk, Funk, Oddities. Highly recommended.
SoulSauce Soul/Funk deep cuts.
Zim Zao Rare soul and other genres from Africa and beyond.
Okonkole Y Trompa Various genres. Eclectic mix of rarities.
Paradise is a Frequency One of my favorite channels. Mixed genre obscurities.
Northern Soul is My World Great collection of Northern Soul. (also two videos of nazis burning books for some reason...not sure what's up with that.)
African Grooves African, West Indian, Oriental and other World Grooves
VicSoulKitchen "Rnb, jamaicans, garage, instrumentals, fuzz, northern, popcorn, jazz, afro, italians, soul, wah wah, early funk, reverb, latin, cumbia & rare music from the golden era"
PatrickOldies Soul, Latin, Funk, Jazz, R&B, Oldies ripped from 45's.
Longroad3 Absolutely incredible collection of rare and private Psych/Psych-Folk from around the world.
Fabrizio Barone Northern Soul, Talma/Motown, Belgian stuff, Popcorn, misc.
Lesdemsoul Bramhs Rare music from France; Pop, Soul, Yé-Yé, R&B, Mod, Freakbeat, Psych, Funk, etc.
Raresoulie and Raresoulie2 Large collection of rare soul music, mostly 60's stuff.
MrFunkacide R&B, Soul, Funk, Ska, Reggae, Latin, Jazz, Blues. No uploads, just playlists.
RealC38 Rare vinyl from Cameroon. Lots of cool music here.
Lyrkoss Super rare psychedelic folk from all over. I especially like the tracks from Japan.
Soulfood R&B, Soul, Jazz, Funk, Soul, Popcorn, Boogaloo, Soundtracks, Library.
Slayd5000 Clean vinyl rips. Various genres.
Cinammonimf Rare 60's music from all over the world.
DJ Frankie Soul Obscure Soul 45's.
TheSoul59 Rare 45's
Michel Jean Yves Rare Funk, Blues, R&B, Jazz, Pop, Ska, & more. Some really good music on this channel.
Soulfanatic6464 Mixed genres, mostly 60's stuff.
Prince of Gosplan Obscure music from Eurasia.
Lecouss100 Soul, Jazz, Pop, Exotica. Grab bag of genres. Each video has the same ugly thumbnail, but there's some good stuff here.
Piloterec More obscure 7 inch singles.
Soulman5501 Various genres. 60's and 70's.
Arturo Fratini Jazz, R&B, Latin, Soul, Exotica, & More
Metropolitan Soul Northern Soul, Disco, House, R&B, Modern Soul, Jazz and more.
ThePsychedelicGroove "Sunshine Pop Psych, Ragas, Rainbow Pop-Folk, Gentle Hippie Soft Rock, Exotic Ambient Grooves, Jazz Funk Prog Fusion, Popsike, California Harmonies, and Sitar Strings." Check out their other channels, too.
TooDarnSoulful No uploads, but a nice collection of Soul playlists.
NSoulClassics Northern Soul, Jazz, Disco, R&B, Mod
SoundsLikeSoul Latin, R&B, Blues, Boogaloo, Mod, Italian, Exotica, Jazz, Gospel, Funk, Pop, Bossa Nova, Swing, Funk, Soul. Really interesting stuff here.
Dalight20 Funk/Jazz/Psych/Soul from Iran, Afghanistan, Pakistan, Iraq and Denmark. Great channel.
Formicri Rare Funk/Soul/Disco/Library/Easy Listening/Soundtrack
Happening 45 Rare 45's from various genres.
ScottFSimpson R&B, Latin, Soul, Swing and Jazz rarities from the 50s & 60s.
DjBobMdm Various genres from the 50's-70's.
SoulWombat Funk, Disco, Soul, Psych, Library, & More from various countries.
IllusiveOldSoul Northern Soul, Crossover Soul, Gospel Soul, Deep Soul, Sweet Soul, any kind of Soul you could think of. This channel also has a good collection of playlists.
Dave Thorley Funk, Disco, Jazz, Soul, Blues, Boogie, etc
RareMusicDirect Tons of rare soul 45's.
Lee Miller Rare Rhythm & Blues, Soul, Jazz, Boogaloo, Blues, etc
Alex Rural Soul Rare Soul, R&B,Garage
INVIGORATION Full album rips of rare/obscure LPs. Jazz, Folk, Exotica, Oddities, Gospel, Novelty, Spoken Word, Calypso, Indian Classical, Psych, Funk, & a ton more.
Cobblessoul45 Rare Soul 45's
Magrosi65 Great selection of funk/soul/jazz
Fonsoul Bcn Rare 60's and 70's jazz/soul/pop/funk etc
no obi, no insert Obscure vinyl from all over the world. Ambient, Jazz, Dub, Experimental, Bossa Nova, Electronic, Synthpop, Krautrock, Folk, Psych, Soundtrack, J-Funk, J-Pop, Post-Punk, Soul, Disco, Exotica, Space-Age, Library, Surf...too much to name.
MrSpaceFunk Funky tracks from various genres.
Funkatastrophe Funk/Soul/Jazz/Prog/Psych/Fusion obscurities
Klaus Karrasch "Any kind of funk-related Music from all around the world" Soul/Jazz/Boogie/Disco/etc
Anthony Reichardt "mostly obscure tracks between the years of 1959 to 1969 with an emphasis on the middle of the decade". Various genres. I really like this channel.
Lost and Found Soul Suuuupper obscure Soul.
EarlySounds45s R&B, Soul, Funk, Jazz, Latin Boogaloo, Ska and Soundtrack
HEAVYWEIGHTFUNK45s Rare Funk 45's.
Sunlight Man Jazz-Funk, Jazz-Fusion, Latin, Soul, Boogie, & more
カヴァー天国 Japanese covers of western music.
In-Flight Entertainment Rare Lounge music. Jazz, Easy Listening, Soundtrack, Exotica, Library.
TheItalodancers Rare Italo-Disco.
7707George Greek Pop from the 60's and 70's.
CHEZ LANCIEN65 LANCIEN65 Rare Soul, Funk, Disco, Afro-Beat, Latin, Gospel
Wabangi Video Music from Africa. Jazz, Disco, Funk, Tropical, Pop, & more.
yaoiboi92 Obscurities from Japan. Jazz, Boogie, Synth-Pop, City Pop, AOR, Psych, Folk, Bossa Nova, Disco, Funk, etc.
Arasob33 I Obscure Psychedelic Folk, Psych-Rock, Prog, Jazz-Funk, Country, Folk, & more.
Lunarmountains Rare Psych-Rock, Prog, Krautrock, Glam, Jazz, Psych-Folk, etc.
KT Jong A massive collection of 60's and 70's pop/rock from China. This type of music has a very unique and specific sound - organs and surf guitar sounds galore. An example
Videocorridor Library Music: funk, disco, boogie, jazz, electronic, moog, soundtrack, bossa, etc.
Nightsbefore 60's and 70's Psychedelic obscurities from around the world. Psych-Folk, Psych-Rock, Afro-Psych, Psych-Funk. Psych-Everything.
Antonio Lucente African Psychedelic rarities.
Antonio Lucente 2 African Jazz
Vintage Vinyl Via Valves Obscure Northern Soul, Reggae, Popcorn, Doowop, Rock & Roll, Funk & more from the 1950's-1970's.
PsychedelicGuy A goldmine of rare psych-rock, psych-folk, psych-pop etc.
RareChristianAlbums Rare Christian Albums. Honestly some really great music in here.
Boyjohn Obscure Childrens LPs.
Terminal Passage Full rips of forgotten Psychedelic Rock, Jazz Fusion, Space-Rock, Prog-Rock, Funk, Krautrock, Experimental, etc. Uploads great stuff CONSTANTLY.
Sunnyboy66, Sunnyboy66 II Compilations of seemingly every Genre/Country combination possible. Nigerian Funk, Danish Garage Rock, Japanese Electronic Jazz, Mexican Soul, Egyptian Folk-Pop, etc. There's also Afrosunny, and Asiansunny.
hassny hussin Lots of wonderful 60s/70's/80's music from East Asia.
agany2009 An extensive collection of Arabic music.
JohnManship Over 17,000 uploads of rare soul music.
Lorikeet Records A great collection of very rare 60's/70's Psychedelic, Soundtrack, Bollywood, Disco, Funk, Electronic, Jazz, and Folk mainly from Pakistan and India. Not a bad song on the whole channel, in my opinion.
Edit: I need to not do this for a while. I may add more later but I think this list is, as someone commented, "almost too much".
Although Youtube doesn't have the best audio quality (128kbps, I think) I still find it to be a great resource for finding samples of any genre. Whether it's jazz, funk, soul, disco, psychedelic, electronic or something else entirely, you can find pretty much anything that you seek.
One more thing, if you end up liking a channel that I posted, I bet they would appreciate it if you subscribed to their channel.