I found someone's github with a method to directly convert the books to epub:
https://github.com/GMMan/Extractor.epub
However, it doesn't work on the current version of the vitalsource software. To get it to work on Windows you need to uninstall the current version install the old version from their site that is indicated as being for XP and Vista:
https://support.vitalsource.com/hc/e...wnload-Options (works fine on Win10)
Apparently it works through the vitalsource program allowing files to interact with each other so someone made up an epub that can extract the actual files from inside the vbk files. I successfully converted 4 out of the 5 books I tried. One wouldn't work but I'm not sure if it is my fault or not.