Seems like a site like this will live or die by the curation. Its not clear to me why I would visit your site versus Hacker News since the community here culls out the startup related posts from the sources you have listed on your site already.

Also, "startups" is a pretty broad topic and there are lots of sites which aggregate startup related content. It seems like you could be more successful by picking some aspect of startups and focusing on aggregating content related to that specific aspect.

As far as video, vator.tv has lots of startup video content. I am not sure about pictures, but sites like slideshare.com have interesting startup related presentations.