YouTube not loading YTC elements

[Mephi-Dross]

Since the latest few versions I have the problem that YouTube refuses to load anything connected to YTC. E.g. I cannot click the little gear to access the settings, any thumbnails take a very long time to load or simply don't load at all and most importantly, the player just appears as a blank black field.

I am using Firefox 28.0 with the GreaseMonkey userscript. I have this problem with the latest stable as well as the last few dev versions. When looking at the console I see these errors when loading a page:

Error: Permission denied to access property 'io'
Error: Permission denied to access property 'config'
Error: Permission denied to access property 'config'
Error: Permission denied to access property 'enabled'
Error: Permission denied to access property 'pubsub-subs'

Edit: I've just installed the firefox addon and it works without a problem. Wish I thought of that before writing this grml.