Categories and Category

How do I make it compulsory for members to choose a category for their newly uploaded photo or video?

Also, does anyone know of a module that allows sub-categories so that members have to choose 2 categories for their uploaded media?

Im also looking for the same thing. Also does anyone know how to delete a user made category?

Okay after playing with my site for an hour I found a way to delete them. What you do is copy the category the user creates and goto you categries section and create it. After you create it, it will show up on your list once its on your list disable it. Then you want to go into your video mod and uncheck the auto approving button. This way members cant add their own categories because they have to be approved by you.