Like the thread title implies, if I have 0.25 media pack, does the 0.30 media pack add anything new?

I know they added a couple of extra videos or so I heard something along those lines.

I can say that older media pack won't work with 0.30. On the other hand you can still play the game without a media pack installed.

Extra movies for new wonders and religions, extra music. If you've got version 2030 (which you should upgrade to from 025, it's far better) you'll need the new pack. Using the 030 media pack with 025 probably won't add anything which is actually referenced in game, and makes no sense anyway :)