same problem...
i have been experiencing the same problem with my mid 2010 i5 15" macbook pro. One year ago graphics related kernel panics with -> logic board replacement. two weeks ago the same pixel-problems as in the screenshots you have posted above, occurring during video conferences, video streaming, youtube, but also the new-tab-top-sites problem in safari as well as black facebook site after switching back to the facebook tab from another in safari.
They have replaced the logicboard again, which didn't solve anything. Now I switched to another service center and the logicboard is being replaced for the third time incl. RAM. I am really annoyed since I need my MBP for work, it has been in maintenance for 8 weeks within a year now and to be honest - apple products are really not the cheapest and therefore I expect them at least to be reliable. Anyone with a real solution here?
If there is no customer-satisfying solution here possible for me, I a.o.th. will have to say, never ever Apple anymore. It just cannot be that this seems to be an issue so many experience and there does not seem to be any solution offered, that really fixes the problem, talking about a product from Apple.