Here is a partial fix.
I have Firefox set to block autoplay vids, and I also created a bookmarklet (look it up) that removes video elements from the web page.
If you see a video playing, you can click on the button in your bookmark toolbar to execute javascript to kill the video. It leaves the video player visible, but it is now empty: it does not use bandwidth and it does not distract you.
Here is the javascript. To use this, you need to create a button on your bookmarks toolbar, and add this as the URL:
javascript:var x = document.querySelectorAll("video");var i;for (i = 0; i < x.length; i++) {x[i].parentNode.removeChild(x[i]);}undefined;
One way to use this bookmarklet is to make a new button by dragging (say) this page's URL to your toolbar, then editing it to set the url to above, and renaming it to FixVid.