I'm sorry but Diaz's story it's an old one and it's bogus. The 'plasma crafts' were real and very impressive, but he sort of stole pictures and videos from other mexican ufo researchers and forged videos where he was claiming to have entered (together with his camera!) a spaceship directly from his garden... I've met him at one of his conferences in Italy, and it was the most embarrassing fake I ever had to endure. He was out and tripping the world only for his own ego and to make money.
Years ago there were many references out on the www about his forgeries, haven't checked if they are online as yet. Only thing I know and watched as it went on and on, it's that he hooked many 'ufo researchers' around, those kind of people with a seemingly outstanding knowledge about the ufo phenomenon, but always lacking 'the crux of the matter' gift. Same old Newageish stuff, so far.