I know you tube won't work if you have any parental controls set, atleast it won't for my son's settings. Most of the videos won't show, even the children's ones. I'm not sure why, unless its because of commenters. You might want to check your settings...there could be factory settings on your computer that your unaware of.
The only time I have ever even used youtube is when Stormhorse posted her videos last week but they worked fine. My photobucket works great too, maybe it is your computer. Might be the popup blocker, maybe need to turn it off on those sites.