Bad news, I have never seen any performance of the play on video or DVD.
There is a compromise. The opera Greek, based on the play, was released on VHS (as well as a CD). The opera is quite faithful to the play, and the atmosphere does give a good feel for the play.
(http://www.iainfisher.com/berkoff/berkoff-greek-3.jpg) (http://www.iainfisher.com/berkoff/berkoff-greek-2.jpg)