How it happened! Answered by the movie director: Dean Alioto.
It seems that it has an even longer and bizarre story behind the "comercial tape".
A small quote from the director: "pparently, someone -- much more crafty than myself -- had made an edited bootleg copy of my video and injected it into the UFO community, hyping it all the way to the 1993 International UFO Congress Convention where it brought the house down. A Lieutenant Colonel with 40 years military intelligence, who was on the panel at the convention, determined right there that the tape was real!"
The whole story at this website:
http://www.badmovieplanet.com/3btheater/a/alienabductionII.html