If you don't like twitter bootstrap (for your css), you could use this: http://www.getskeleton.com/ It's light enough, and provide a good starting point.
Add colors, borders, and shadows later. Focus first on layout. Come close to screen, and look for details. Go a bit far away from your monitor, and look again the entire design. Sometime it helps to get a better overall view.
I think bootstrap is great... Also I was thinking about something like http://suprb.com/apps/gridalicious/ for the videos grids;
The tricky part is that these grids have reactive behaviour on resize (actually I think the response to resize it's one of coolest features, in that the number of videos shown will adjust whenever you resize the browser window, so that everything still fits on the page). So I always need to be able to compute on the fly how many items will fit on the screen, because if the window is smaller than its fullscreen size, then I can actually avoid to retrieve any data for videos that won't fit, and hence cut bandwidth usage and response time.
Also I appreciated the RESTlike interface, kinda cool you can share searches on facebook or twitter (G+, no one cares :D!)
The graphics design: it's a little bit messy, I'd like to see a more coherent style.
You're right about the design: I built the current one kind of incrementally while adding features, and I'm not a graphic designer either - but I guess you could already tell!!! ^_^. So I'd definitely need to start fresh with a clean design... I'm striving for the help of a professional, actually.
Thanks again, I'm flattered :)
