This appears to be just the plugin I'm looking for, so thank you for writing it!
Unfortunately, there seems to be a small bug in it, when it comes to network shares. It doesn't appear to be able to delete any files accessed through smb.
Doing a little digging, I've tracked this down to the use of os.path.normpath. When Movie or Episode (in service.py) gets the file path from the json API, it will have a path something like "smb://server/share/folder", which is then passed through os.path.normpath before being assigned to self.path. Normpath then completely mangles it, producing "smb:\server\share\folder" which isn't going to work for anyone!
I tried simply replacing the line
self.path = os.path.normpath(p)
and that makes it work (for my particular case!), using the alternative deletion method (so using xbmcvfs for the file operations).
Ideally, it would be nice if the plugin could simply request xbmc to remove the video from the library, and let its default handling do the deletion (rather than delete and request full cleaning). Unfortunately, as far as I can tell from a cursory inspection of the API, it's completely impossible to remove an item from the library using the API. Which is a shame.