This is a short film of the Gnostic Mass that was made by New Aeon Films at Blue Horizon Oasis. I'm the Negative Child (the one in the black mantle following everyone else ;).
An artistic short-short, "Impressions", is freely downloadable on the site. While it doesn't give you the nuts and bolts of the ritual itself, it does a wonderful job of conveying the feel and emotion of the Mass.
(Thanks to elqahar for the pointer - I had no idea this was online! Squee!)