The very first answer is… are you connected to WiFi? If not, you know what to do…

The second answer is that you need to replace these 3 YouTube fix files in the /var/root/Library/Lockdown folder of your iPhone. So you need to connect to your iPhone via SSH and replace the existing files with the ones from the download above.

Reboot your iPhone and then, usually, it works.

What? That’s not enough? You can only access the bookmarked clips from YouTube? The answer is very simple, even if I don’t understand why this affects YouTube on the iPhone Have a look at the date and time of your iPhone… I’m almost sure that it is set somewhere in 2015… Correct it and it will work!!!