It's up to the teams but if I were one I'd definitely submit a pitch video.
It's in their interest if they want to give a better idea on who's behind the project and what it is about, how they came up with the idea, etc.
Also as a registered "fan" of the hackathon a video goes a long way, I'd prefer it to trying to figure out code instead.
I'm also looking forward to see the project's decks, oh maaaan a lot to check out.

 

Is Joel Dietz involved in this at all?