Probably a repeat here, but I want to focus specifically on amateur actors/musicians/whatever who have put their stuff up on YouTube that particularly stands out in your mind.
The case that inspired this thread is rather obtuse to most, but I’ll toss it out anyway. There’s a Japanese role-playing video game called Persona 4 (look it up on Wikipedia if you like). It’s generally acknowledged as quite a good game, but it, like almost anything regardless of quality, is ripe for mockery. A LiveJournal-er with the handle “hiimdaisy” has been writing and illustrating a comic parodying the game, hanging a lampshade on all the plot and characterization weirdnesses. Someone decided to take this comic and dub it.
I’m quite impressed at the quality of the voice actors this person assembled for the dub. The narrator, for instance, has quite a good announcer/narrator timbre to his voice, which makes his funny lines all the funnier. But they’re all excellent; I wouldn’t be surprised if we’re listening to the next Yuri Lowenthal or Rob Paulsen somewhere in there.
Not sure what to do with now-legend on the uke Jake Shimabukuro. The guy is a total monster - his version of While My Guitar Gently Weepsis brilliant. He may or may not have been pro, but was unheard of outside of Hawaii before Youtube. This and other videos have paved the way to a broader pro career for him…
Rite of Spring on guitar This guy used a guitar and very few effects to play all the parts (not at the same time though) of the opening of the Rite of Spring by Stravinsky.
This drummer is pretty amazing. Maybe he’s somebody famous in the drumming world, but he looks to be a college marching band type drummer, so I think he’s an amateur.
It’s likely everyone’s already seen this, but Groovy Dancing Girl (Sophie Merry) deserves a mention. She parlayed her YouTube fame into an endorsement deal for a clothing label (that one might be even better than the original).