presumably Silence Of The Lambs - as I'm sure (along with Spinal Tap which was a DVD 10) that this was the first Criterion disc to actually be released.
THE SILENCE OF THE LAMBS was not the first Criterion DVD. I'm not entirely sure of what the very first Criterion DVD was, but I know that John Woo's THE KILLER was in the first batch of Criterion DVDs, and that was some time before the release of THE SILENCE OF THE LAMBS. I think THE KILLER was a DVD-5, too.