How to add content description to video file...

Please help....this is not necessarily a Premiere Elements question but more of a general video file question.   I am collecting all of my family's videos and creating numerous different movies. 

Aside from the name, I don't see where or how I can include some sort of description of the contents.   I know there is a comments field in the details tab of the file but I am not able to add anything to that field.   Does anyone know how I can do this so I know what is in the videos?

Thanks.