That's why you play the game yourself. Record yourself playing, timestamp the parts you know you'll want to use for your video. You probably won't get them all and will still have to do some digging every now and then, but it should be easier to dig through your recent playthrough versus scouring to get the clips you need.
Unless you're just talking cutscenes in which case I'd argue that's easier than ever because pretty much every game has multiple playlists that are just "story of X game," many of which are literally each cutscene as a separate video so you don't even have to scroll through a 3 hour long video to get the one you're looking for. Again, it doesn't completely eliminate the need to search, but it definitely cuts down a significant amount of time.
But, hey, I'll actually agree with VB for once, she's right that her videos are better off when she doesn't physically appear in them and I'll gladly encourage her to keep taking whatever steps are necessary to avoid showing herself on camera.