Rated 4 out of 5 stars

lately the html5 video player controlls are gone until you once disable the addon , play a video and then enable it again.

This user has a previous review of this add-on.

You might want to look at https://discourse.mozilla-community.org/t/how-to-determine-the-mime-type-of-the-loading-document-in-a-content-policy/9917?u=desktopd