Sorry...
My experience is not all that broad, but I don't think there is an existing solution for what you are trying to do.
I researched something similar a year or so ago...actually, it was kind of the opposite. I was looking to capture JPGs from a playing video. There was no way to do it without having something custom built or knowing a lot about how video files are encoded.
I would presume that if you really knew what you were doing, you could ingest the current Windows dekstop screen print into your VB program, and *if* you somehow knew what part of the screen you wanted, you could section it off and store it.
In terms of turning the JPGs into video, that's another thing entirely. While there are plenty of tools to do that, you'll probably run into what I run into. For tools like that, they are all end-user tools with a GUI on the front of it with no exposed SDK. You'll have a hard time finding something you can use as part of your VB program.
