This post gives you a step-by-step on what to do in order to get uBlock to filter out youtubes stupid pop-up effectively! I originally saw this info from This Tumblr post and it has some important info regarding not inputting your own filters due to youtube regularly changing to get around them, so if you're just using a filter on uBlock you might want to consider doing this ...
P.S.: I'm not tech-smart so I can't help anyone who's still having issues in the comment section sorry 