One thing to try ...

Enhancer for YouTube™ – Get this Extension for 🦊 Firefox (en-GB)

the enhancer YouTube is something that I have used for some time on Chrome, (the above link is for Firefox)...

Works fine here, just to prove it's not a geographic block issue

Edit

Just to eliminate the possibility My Browser is chrome- if you are using any other browser, that could be the cause - try...