Safari 4, choppy video on iBook G4
Videos played in Safari are choppy on my iBook G4. Sound plays OK. Everything was fine last week, the only thing I did is to delete my girlfriend's account and create a new account for me since she's not using the computer anymore. When I did that I was asked to upgrade Safari to version 4.1.2 (or something like that, I know for sure it's version 4) and since then, I can't look at Youtube videos or any other videos site. It's not a network problem since the video is downloaded faster than it plays. My girlfriend says she had no problem before I did the upgrade, I can't figure out wich Safari version was installed before I upgraded it. What should I do, go back to version 3.??? or is there something I should try before attempting to revert to version 3.
thanks for your help
G5,DP, 1,5Gb + MacBook Pro +iBook G4, Mac OS X (10.6.2)