Adding tags to video files

[Snyper]

I did a quick search but was surprised to find nobody has mentioned this before.
I have a vast library of video files and clips. Naturally, these are sorted into genre folders which makes it easy to find specific types of clips, but I'd really like to be able to both search, and create playlists from aspects of the clips. For example, Actors, type of footage, etc. I'd love to be able to add specific tags to media files, probably stared in some sort of database or something to allow this.

Alternatively, if we could add notes to files, we could add in whatever information we want and if we could then search the contents of notes that would achieve the same result.