Permission for vid shows/parties?

[damned_colonial]

In late May, at WisCon (a feminist science fiction convention with a strong contingent of fanwork-friendly media fans), were_duck and I will be hosting a vid party. It's not a very formal event -- we'll just have a room and we'll be playing a bunch of vids we like or that people have recommended to us. We're thinking we'll open with an intro to vidding and some show-and-tell, and then at a certain time of evening we'll declare it "party time!" and just play vids from a playlist on one of our laptops.

Our plan at present is to attempt to contact vidders to ask for their blessing to show their vids in this situation. If anyone says "no, please don't" we won't. But if we can't get in touch with people, or they don't reply, we're thinking we'll assume it's OK as long as the vid was publicly posted (i.e. not on a password protected website).

Does this sound reasonable? We're open to suggestions if there's a better way of going about it.

ETA: if you'd like to pre-emptively give us permission to use your vids, and save us some legwork, please do ;)