Learning_Curve - 8:02 pm on Mar 26, 2012 (gmt 0)
Well, I imagine you could insert a new video in front of the old one and then delete the old one. Technically I can't see why that wouldn't work. SEO-wise, however, it may not work great if YouTube dings the video because of the changes (I am totally guessing here). I imagine that YouTube will reevaluate the video.
For example, last weekend I edited the information (not the video itself) on a series of closely related videos and created a playlist for them.
One video that previously ranked well for a particular keyword (video appeared on first page of Google proper) fell out of the video entries on Google proper and was replaced by another video (not mine).
Maybe it will bounce back.