I don't know if this program had anything to do with it, but I downloaded "TuneUp Utilities 2012" free trial version and ran it and now YouTube is not buffering on the video it was this morning. I can run the video in 720p and it loads fine. I'll monitor it to see if it continues.

Edit to Add: It's loading fully and faster than it ever has.  I'm hoping that the issue was my computer and not UV.