So I watched youtube now (9:30pm) and was on "Paris - paris" The first second it loaded with 1MB/s but starting from the 2nd time that it buffered, it never went above 300kB/s again.
So I switched to "London - turing" and there I got only 200-300 kB/s again. So there is no improvement.
I then switched to "Frankfurt - cantus" (geographically the nearest) and it was even worse. Started the video from beginning (F5) it loaded 1MB/s for split-second, but then it after a while it only got 50kB/-200Kb/s averaging around 150kB/s at most.
Then I disconnected the VPN and only got 150-300 kB/s as well, in that way I can't view 10 seconds of video till it starts rebuffering.
Seeing, that it got worse the closer the Endpoint of the Tunnel was to my place, I guess the Youtube CDN server in my country is overloaded.
So the solution might me, to selected a VPN server that is far away??
EDIT: The behavior is so different than yesterday. Yesterday it was clearly better without using the VPN connection. Today not so much
another EDIT: It now seems to bee bad every where, Iceland server = less than 150kB/s, US central - mishigami (with UK ip??) as well bad, less than 100kB/s, but now also Frankfurt below than 100kB/s and not 300kB/s like I wrote above.