Jumpy YouTube

Hello all.
Recently, YouTube, Vimeo etc have become incredibly jumpy (even if I let them load up first).
What can I do to improve this?
I use Firefox on a Lenovo T61 ThinkPad.
All help is gratefully received
Answer #1
You mean freezing during playback? Is your flash player and video drivers up to date?
Could be your internet connection, make sure it is sufficient enough to stream as well.