I know this type of error has been reported a few times but as I have not found a suitable solution, I will post this.
Trying to watch anything on firefox browser, get error code t:3222/c:4110, whether signed in or out. Tried all the steps numerous times (right-click silverlight; ensure correct boxes are ticked, uninstalled silverlight, disabled ad-blocker).
Interestingly, it works fine on IE browser but I really dislike using it, so would much rather get it working on firefox. Use to watch on Chrome but thats obviously not an option anymore. 
Is there anyone who has had a similar error message to this and somehow managed to get it working on firefox? Thank you