As an aside, hats off to Google to being able to serve an 11 year old video with no noticeable delay from what must be the coldest of caches.
Which I now just realize why they did that : a lot of people didn't understand the difference.
Sadly, a lot of other people did understand the difference, and did not expect this kind of switcheroo, and now there's a bunch of effectively dead links covering more than a decade of videos.