Its usually games, though its generally "whatever we are doing at the time" with trusted, long distance friends. Its not something I would want to share over publicly accessible URLs. And it almost always involve varied and fast moving visuals, so basic software encoding is not acceptable.

I have tried jitsi before. It does not use hardware accelerated codecs or provide audio isolation for applications. I can't imagine using its screen share for anything more demanding than a slide show presentation.