Earlier quoted context omitted.
YouTube uses encrypted signatures as a way of hiding the URL of the video. https://github.com/l1ving/youtube-dl/blob/master/youtube_dl/...
It's like closing the door and hanging the key next to the door for all to see. Definitely not an effective technical measure to protect the house. EDIT: And not to forget that Youtube hosts many CC-BY licensed videos which explicitly allow unlimited use (incl. decryption if necessary), and that Youtube has contracts with copyright collectives in most countries so for any user it is save to assume that the video is l…
That's a highly questionable statement. Certainly, most European countries do not have such a law in all circumstances, and it's dependent on if the personal use copy is made of an asset you are licensed to have permanent access to (which you aren't of a collectively licensed work) or a broadcast for timeshifted purpose (which an on-demand asset isn't).