Thanks for your reply. I got the video portion to work by choosing the 32-bit version of InternetExplorer 8.0 (before I was using the 64-bit version). However, I still have no sound. Could re-loading Adobe Flash using the link you provided fix my "no sound" problem (or was it only intended for the "video not playing" problem)?
As I mentioned before, the sound works fine for all other things (such as news video clips, Crutchfield tutorials, etc.) - just not for YouTube.
Edited by GWBlack, 12 December 2010 - 10:26 PM.