Hi,
This sounds familiar.
What video are you trying to watch and in which browser?
We found an issue with WMP / Metro video causing what you described - the workaround was to disable "Turn on DirectX Video Acceleration for WMV files" in Windows Media Player."
The issue I describe is fixed in the next release - let me have details of the setup you have so I can confirm that your issue is fixed as well.
http://www.displaylink.com/support/ticket.php?id=269
Thanks,
James