You probably made an uncompressed AVI. Unless you have a RAID setup, your computer cannot play back uncompressed movies of any type, AVI or Quicktime. The movie needs to be compressed. In any app that makes videos, the video is compressed using an algorithm called a codec, which is short fo COmpressorDECompressor. The codec is chosen when you choose to export or render from whatever program you are using to make your videos.
So. You should compress to which codec? I don’t know. This is now a Dreamscenes question. You need to look on the web, and find out what the Dreamscene-maker will accept from you. MPEG? MPEG-2? WMV?
Now it is common to make uncompressed movies that cannot be played back, but are sent to another application that makes the playable file. Maybe there’s an app that accepts AVI movies and makes them into playable Dreamscene movies? I don’t know — that’s for you to find out.
At any rate, uncompressed AVIs can’t be played on most computers. Try searching the web for “AVI” and “dreamscene” to see what you need to make. Then get back to us if you don’t know how to make that (MPEG or WMV) in AE.