This is extremely simple. I don't create many clips, only when I do something cool in-game. So like at max 5 clips per day, more like 1 on average. My game recordings take up gigabytes but would be in terabytes if I did not clean it manually.

Right now I take the clip and manually copy it into a folder for clips. And then when I am purging old recordings I can just ctrl+a -> delete. But the minimal viable help you could provide me is:
If you are using match / session / (or rounds in case of CS2) mode, you can select a specific folder for favourited clips where they will be moved manually under the game identifier directory for easier finding.
This way I can just go in there any time, find the clip I want, go out, go into recording directory and do my standard "ctrl+a -> delete" without worrying about removing good clips