VNC server fails to start: Fatal server error: Couldn't add screen
817.
Remove the 32 bpp setting and use 24 bpp instead. You can try to run shotfactory.py -vvv (for very very verbose output) to see the exact commands that the shotfactory script is trying to run.
818.
Sometimes the automatic scrolling doesn't work. The reason could be that your page uses frames, or that it sets the keyboard focus to an input field with JavaScript.