For live streaming and recordings, please think about licenses. The presenter
has to agree to put his/her talk under a free license. Sadly, most of the videos
from Buenos Aires we have on commons are technically copyright violations,
because the presenter's consent is missing.
I highly recommend to require all presenters to explicitly state the license of
papers, slides, and the presentation itself. For the Developers' Workshop I'm
organizing in April, I made this question part of the registration form. I
recommend to do the same for Wikimania.