Some programs have different versions of File types When you render video.
Sometimes the Video Format simply isn't compatible with the video editor.
You may get it to work a few times but that halt in production, bump in the road.. stops reading your shit, likely not compatible.
The only thing about switching up programs is different versions of the same file type, comes with possible change in quality.
Just what I've learned figuring my setup out anyhow!
If you capture in a program called virtualdub There is an option to make that capture "Full Process"
Without selecting that option your output AVI file won't be compatible in vegas.
Look around, if there's options toy with them.