YouTube tag not always working

I tried to post a YouTube video earlier and it wouldn't appear. I tried to figure out what I was doing wrong so I looked at other videos I had previously posted with the YouTube tag, and they seemed to be working just fine. However, when I clicked the Edit button to view the tags, "YouTube" and been replaced by "Flash" accompanied by a set of dimensions at which to set the video. I didn't use the Flash tag to post them before, but they were Flash tags now and I'm not sure how or why.

When using the Flash tags to post the YouTube video, it showed up just fine. Before posting about the tags here, I again tested a video I previously posted using the YouTube tags, and it again worked fine. (Below.)



But if I replace the URL with the URL for the video that failed to work earlier, the tag again failed. The video doesn't have it set that it isn't allowed to be embeded elsewhere, and as I said it works fine with the Flash tag, but not the YouTube tag. Is this an error with the tag's scripting or something? Do perhaps certain characters in a YouTube tag URL somehow mess it up?

I would post the video that I know is giving me trouble, but it's a video of the Republican Space Rangers bit on Grand Theft Auto IV, which is full of colorful metaphors, and I didn't want to come in here fowling up the place with all that.

EDIT:
Just in case, I did hunt around on here for YouTube-related stuff, but none of the topics I found mentioned this issue in them.