is robin williams on the dvd version

i got the return of spinal tap dvd in the mail today from amazon.com and i watched it and i did not see robin williams anywhere in the movie i heard somebody say he was in the laserdisc version is he not on the dvd version i watched the credits and it said in the credits special thinks to robin williams and he is listed in the cast on here is he just in the laserdisc version or what