Mac OS X: Folder action

Dear readers

As ATV is Mac OS X, is it possible to have folder actions installed/activated?
I need to decompress files from http://www.onlinetvrecorder.com to be able to watch them.
For this, I need a automatic folder script which does decrypt the OTR file into a AVI file to watch.

Any suggestions and tips to do that automatically through bash or apple scripts are welcome.

Kind regards
Thomas Thaler