Also, imagine if we got a dollar we had to downgrade versions, as well as the times we have had to uninstall the current version.
After uninstalling, I tend to then do a reboot, as it only takes an extra minute, then look for any streamfab leftover folders, then use the offline installer to install again.
Sometimes you can just go to
%HOMEPATH%/Documents/DVDFab/StreamFab/
and delete folders there, at least the temp and logs folders, at minimum.