I'm using Firefox 54.0.1 (X64) with ublock origin and the video plays okay. Does take a few seconds to start though.
PLEASE TURN OFF YOUR AD BLOCKER This video is unavailable if an ad blocker is running. Please disable and reload the page to start the video. --- I'd rather not see the video than disable my adblocker
Hi Mr.X yep after release Firefox 55 you already see in Extensions that severals extensions now is show as Legacy then try see my post in this section from some days ago about this behavior still in time wait for Firefox 57 big changes arrive