One of my all-time favorite type of videos is pre-fame bands playing their extremely famous songs to a tiny room of people, because they're not yet known.
A thread of some examples:
Bastille playing Pompeii in what looks like someone's living room:
MGMT playing 'Kids' to a crowd of maybe 25 people on a college quad:
Tones and I playing Dance Monkey in a parking lot before the song came out