The Media Center here at Blackberry Forums is a great place to search and find some. As far as other apps, the phone hasn't been out too long but m certain there are apps being developed at this time. Depending on what kind of stuff are you looking for. Games, at this time, you must by. try Nintaii, its awesome and i bought it.
As far as the video, i personally, think 3gp is good. But thats might take, might not be yours or others, but i thinks its all the same...
Try this link for a list that a current BBF member made of the ones that do work, and google search them.... 3rd Party Applications for the Storm
And the Media Center.... Media Center - BlackBerryForums.com : Your Number One BlackBerry Community