I find it kind of funny that they would choose to show those as demos when it's obvious that most of them really aren't Youtube video IDs. Like "Accept-Lang" is pretty obviously not actually a video ID, even if it matches the [A-Za-z0-9_-]{11} pattern and technically could be a valid ID.

On the other hand, I don't know how you would actually verify whether an 11-character string is or isn't a Youtube ID (short of querying Youtube itself), so I suppose it's nice that potential IDs are shown, just seems they have a very high chance of being false positives.