Add &disable_polymer=1 to the end of the url and see if it's different. Here's an add-on to do this automatically: https://addons.mozilla.org/en-US/firefox/ad

Add &disable_polymer=1 to the end of the url and see if it's different. Here's an add-on to do this automatically: https://addons.mozilla.org/en-US/firefox/addon/disable-polymer-youtube/?src=search https://addons.mozilla.org/en-US/firefox/addon/disable-polym...