Msg#: 4486508 posted 3:44 pm on Aug 20, 2012 (gmt 0)
From the YouTube products forum:
You may have noticed a change with tags on the video page when you're watching a video.
Tags no longer appear on this page - this isn't a bug, but a change that went out this week. Having them on the watch page, in some cases, gave users an opportunity to abuse tags by copying them from other videos. We also didn't see much usage of tags by the average viewer.