Rejections appear to be irrational, the upload system is very cumbersome, and I've got material still waiting to be inspected that was uploaded in November of last year.  No sales on 172 items in my portfolio.  Draw your own conclusion, of course, but I don't upload to the site any more.

I submitted my entire portfolio (400 clips at the time) to mediastock.ca about a year ago. It's a non-performing site, with no sales. So no matter what the percentage to the artist is it doesn't matter, because it doesn't generate any traffic! I wouldn't base my choice of where I sell my footage on the percentage, as most of the dysfunctional sites offer great splits. I've generated a working list of sites based on actual income produced. You can see my breakdown of this at:

http://www.stockvideoseller.com/public_html/where-to-sell/

You can also access the resources section and see the breakdowns of other stock footage sellers, by following the links.