Thanks for the help everyone. It works much better now.

With the swfdec plugin some of the videos that was very hacky before on Youtube now runs smoothly.

I have 2 questions in the topic still:

1) How do you get rid of the annoying error message on Youtube (right bottom) "Youtube download - Error Alert
There was an error and the files couldn't be loaded. Please copy the URL (address) and report the problem + URL to"

2) Is anybody able to see this video that I can't: http://www.youtube.com/watch?v=pRVlUthxzrg
Someone said flashvideos can be converted on the fly - but this one is not converting for me at least?

//Tomas