I think I may have found the problem. Give this one a try.
This version will also output a 'debug.log' file in the folder PostHaste is run from. If AutoXvid still doesn't work for you, copy that log file and paste it in the forum for me, if you don't mind.
edit: Also forgot to mention that I made it so you can edit an entry in the configuration window by double-clicking on it. Just a minor convenience.
edit: Check the first reply for this and future updates to PostHaste.