I'm assuming the videos you are trying to view a flash videos (e.g. YouTube, etc.)?
I have a laptop with somewhat comparable specs (ThinkPad w/ a Celeron M @ 1.6Ghz, 2GB RAM, ATI Radeon 200M), and I have the same issue; I believe the problem is that your tablet is simply not powerful enough to run these things comfortably. Please note that my laptop is about 5 years old, so I don't know how the processor architecture compares to the Atom.
In any case, you could try using Firefox or Chrome to see if they may be more efficient.
EDIT: fixed spelling error
Edited by MadDawg, 12 June 2011 - 02:02 PM.