I have filed a bug for this :
https://bugs.launchpad.net/ubuntu/+sour ... ug/1529425
Basically, I used to be able to use SMTube and uget to record YouTube videos.
Now, I always get the "No Video Found" window, with "It wasn't possible to find the URL for this video" text.
I tried the same thing with wget, with the same result.
The bug report has all the particulars, along with screenshots and text files.
I just wondered if anyone here had had the same problem (and hopefully had solved it).