Google YouTube HD Player (malware) has been blocked for your protection.

Why was it blocked?
This is a malicious add-on that tries to monetize on its users by embedding unauthorized affiliate codes on shopping websites, and sometimes redirecting users to alternate sites that could be malicious in nature.
Who is affected?
All Firefox users who have installed this add-on.
What does this mean?

The problematic add-on or plugin will be automatically disabled and no longer usable.

When Mozilla becomes aware of add-ons, plugins, or other third-party software that seriously compromises Firefox security, stability, or performance and meets certain criteria, the software may be blocked from general use. For more information, please read this support article.