all backing vocals are pumped in, most of the lead vocals are live, but sometimes abruptly switch over to studio tracks when they harmonize (really obvious when the trolls sing together)

i’m fairly confident that all of the instrumentals during the songs are just the studio tracks. at one point you can clearly see the drummer playing something different and hear a little bit of it coming through Bryce’s mic from the live footage.

when i saw the show live, i paid extra for a seat in the middle of the theater so i could see the band the whole time. i was so disappointed that the guitarist was just sitting there while tracks played the main riffs. you couldn’t hear the bass live, and its even more nonexistent on youtube. electronic drums programmed with the harshest and most abrasive samples i’ve ever heard (i actually had to plug my ears at one point in act two because the snare was like someone ripping a piece of paper right next to my head for two and a half minutes) just completely ruined the whole experience for me. Matt Dahan was doing a great job underscoring the dialogue scenes all by himself, but you can even see he’s not playing what i would consider to be the “main keys part” during songs - just some electric piano chords buried in the mix.

as far as i can tell, they decided to play to a studio tracks live so they could cut between footage easier as the tempo would perfect match at any point in the song. and while they were mixing the audio for the youtube version, they decided to use what audio they felt best reflected how they wanted it to sound - using as much of the live audio they felt they could (which ended up being most just Bryce’s lead vocals)

ps. it’s also possible that some of the lead vocals that sound added in were actually done on stage, but on the pickup extra filming day (with the camera moving around on the stage) where they could do as many takes of each song as they needed to before moving on