Youtube player (malware) has been blocked for your protection.

Why was it blocked?
This add-on is malware, doing nothing more than inserting advertisements into websites through iframes.
Who is affected?
All Firefox users with this extension installed.
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.