Proper normalization for media with multiple types of owners

[JeremyC]

I am having a hard time deciding on the best way to approach this problem. I am trying to set up an app in rails where users and groups of users can both upload media to albums. The media can be either images or video. I have put together a simple example ERD to show what I have so far https://docs.google.com/file/d/0B8eu...it?usp=sharing.

1. What would be the best way to normalize this further?
2. Should I separate the video and images into separate tables all together and not link them to the media table?

Any suggestions are welcome.

[guido2004]

Why do you have separate images and videos tables? Why not add a mediatype column to the media table?

[r937]

for medai, videos, and images, do a search for supertype/subtype

the videos and images should not have their own PKs, but rather, their PKs should be FKs to the media table