Heh, I kind of wrote this thread off as "dead". I actually am currently trying to implement the AVIFILE API that Windows uses for AVI files. I got to the point where I could load a file, and grab some header information, but once I got a pointer to a packed DIB, I kind of was at a loss as to how to push it into an image. But I'm getting a little help from another PB Programmer currently and hopefully I will be able to do something with it.
Since you are using VB you should check this out. Maybe you can do something useful with it..
http://www.shrinkwrapvb.com/avihelp/avihelp.htm
The guy helping me also might be looking into Inc's Avisynth C API Wrapper for PB, so I guess if the above method fails for getting actual frames, hopefully he'll be able to simplify things for me.
Hope that link helps you, though.