nostr:npub1tzw6a8akxjeqv37etnfrkxxsaeu306rutu0ymsy2z5pszf8p5myq0qyfvk

Thumbnails do seem to matter more than they ought to. Put a human face with an intense emotional expression "reacting" in the thumbnail and a picture that raises a question "what's in the mysterious cave" -- an ambiguous image that people will want to see more clearly... that stuff "works"

But why does it work? Because it's better communication, and better represents the video? Or because someone decided that it works and so those who do it get boosted? Who knows!