I'd clear it out, but there's no function to do so.

Thanks Google, I really love seeing shit I labelled as "Watch Later" in my home feed from a decade ago.

I stopped doing that, half of the times the videos stopped being available. Fuck that.

If I really want something I save it to disk as soon as possible.

My watch later is so big; it breaks whenever I add a new video. I have to manually go into the playlist, change it from recently added to a different listing order, then back to recently added for it to show anything I've added since the last time I've done this.