Vintage gaming community.
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He's not exclusively N64, he covers a wide array of topics, but you could probably find a few decent videos from The Gaming Historian.
Same thing with Nintendrew, and MetalGamerJesus.
Edit: Sorry, I had the wrong name. His name is actually MetalJesusRocks. Brain fart!
In the same vein as MetalGamer Jesus, Game Sack has some N64 episodes as well.
ThaBeast721 if you're looking for plot and gameplay summaries. ThaBeast is on a challenge to complete every N64 game.
There's Nerrel who is both very entertaining and knowledgeable/informative about the N64 and emulation. He does use strong language so just wanted to point that out in case that isn't your cup of tea.
MetalJesusRocks for some "hidden gems" type of content.
MVG for technical or development deepdives.
Karl Jobst for speedrunning content.
Retrogamecorps, Taki Udon, Wulff Den, and ETA Prime for emulation.
All those channels cover various content besides just N64, but they've made some of the best N64 game related content.
He's criminally underrated but does deep dives on tons of n64 games. Really enjoy his content.
KazeN64 a super mario 64 modder (that run on real hardware) with pretty in depth technical descriptions of how N64 works, how it was misused and how it could be done better.