I use this addon to block annoying podcasts and other uploads from channels I usually like. It seems to work perfectly, including in the sub feed (I suspect the underlying requests rather than the page DOM are being filtered, but I haven't checked the source code). My only suggestions would be to add an option for tags, or to include a short "how-to" text on the options page itself without having to click through. Maybe even a quick Regex tutorial for newbies would be useful. Still, this addon gets the job done and causes no issues.

I first encountered BlockTube a month ago when its creator posted it on /r/firefox. It was then in beta and some of its functionality was limited to regular expressions—something that has since been much improved with a new UI. Now many of YouTube's annoyances can be fixed without hassle. Front page auto-generated playlists can be permanently removed through a checkbox and clickbait titles can be filtered by adding keywords.

BlockTube's “Block Video” and “Block Channel” features are so seamlessly integrated that I initially thought that they were added by Youtube themselves. Excellent!

A bit more complex than alternatives but that allows you more control over what you filter on YouTube, all in all, a great addon.