Mark videos as watched

Hi, this is my first post here. I'm very experienced with MS Access, and I am quickly learning HTML and PHP.

What I want to do now is mark a video as watched automatically when it is opened. I want something as close to windows explorer as possible, possibly even an extension.

I'm not sure what avenue I should take to figure this out. I'm looking for advice on how to accomplish this. For instance, where is the data stored? I don't think all file types have the same meta data. How can I change said property on double click (or enter). For actual playback, I only want to shell it and let the default program take over. I even considered modifying the vlc source code, but the meta data issue might work against me.

I'm only looking for brainstorming. Thanks all.