Call me an idiot, but...

Why do movies need to be in blu-ray to be high definition, when games on the 360 are in HD but just on standard DVD?

Some movies are too big. Less not forget either 5.1 or 7.1 audio.

they just can't fit in 8.7 GB. As it is, many new games barely fit in a dual-layer DVD.

so... movies are larger than games..? i never figured that..

I believe for movies they like to use as little compression as possible. Sure it takes more space, but it's meant to look a little better since you can lose some quality as you compress. In games they may use compression and most games probably don't have 2 hours of cutscenes.

Usually yes. And prerendered trailers in games are also pretty big. It's the reason Lost Odyssey was on 4 discs.

consider a 2 hour movie in true 1080p, several audio tracks, including 7.1 Dolby HD, and sometimes uncompressed PCM 5.1 or 7.1. Add to that the extras, HD menus, etc. No way you can fit all that into a DVD.

yes full HD movies 1920x1080p are huge and uncompressed 7.1 audio is too.

going over 15-25 gb.

Its because TRUE 1080p picture and 7.1 surround sound cannot fit on 8.7 GB. The x360 uses a built in scaler to increase the resolution in games but it dosnt look quite as good as true HD picture. Its alot like an upconverting DVD player it looks good but true hd picture looks much better

When a movie shows a street every frame of video needs new information for every frame. While when you do a street in a game the texture for the street and any objects in the street only need to be on the disc once. Not for every frame.

So lets say you load up the first level of Halo 3 and don't move for 24 hours. The game only needs a couple of hundred mega bytes on the disc for the game level. Where as if it was 24 hour video file of the game level it would take several Blu ray discs to hold the file.