How do I archive a video before it gets deleted?

Working on a documentation project on my own, and I keep losing material. Twice this month, I have gone back to something I bookmarked, and the whole account was gone.

I know the answer is "save it immediately"; I just don't have a proper routine, so what I actually have is a folder full of files called video_final_2.mp4 with no idea where any of them came from.

Looking for something that is not overkill for one person. Specifically: what do you save alongside the file so that six months later you can still show where it came from? And does anyone hash at the point of capture, or is that only worth it if the material might end up in a legal process?"