Hi Shane.
The way I understand it is the the avi only acts as a method of stitching individual bmps together and at 640x480 each bmp is 901kb.
There are three things you might want to consider.
1. don't compress your avi. Leave it at the larger size then run it through Registax. You will get better adjustment with your final image and achieve better results with the least compressed avi. 250 meg files are not uncommon for me. Even 500 meg happens now and then depending on what I am shooting.
2. Even though you will get less frames, think about capturing at around 15 fps. Any faster than this and your images start to suffer from compression. The standard is usually around 5- 10 fps.As a general rule, if the seeing will allow it the slower the better with a ToUcam. One thing you can do if you don't have tracking is to collect a series of avies and then join them together with Virtual Dub (free) or convert all your avies to bmps (again using Virtual Dub) and then run all the bmps together in one run through Registax. It is a lot of work though.
3. If you haven't already done so, have a read of Iceman's
Astrophotography with a Dob . He has been through exactly what you are trying to do, planetary imaging with a non-tracking Dob. We are still wondering about his sanity
