Some of my rarest videos (minus flat-out bootlegs) would probably be:
Current 93 - Since Yesterday VHS (someone stole my original and I had to replace it in recent years... aaargh!)
Elijah's Mantle - Philosophy With A Hammer VHS
Der Blutharsch - Gold Gab Ich Für Eisen VHS
Fire+Ice - Live at Hammersmith VHS
Coil - Live in NYC VHS
WaxTrax! Video Sampler #1 VHS
WaxTrax! Video Sampler #2 VHS (both of these are original promos sent out from WaxTrax! back in the day)
Laibach - Predictions Of Fire workprint VHS (may or may not be a bootleg)
Jefferson Starship - St. Charles 1976 conceptual video DVD (my own transfer from the original 16mm film)
The Trap Door complete collection 2xVHS (very rare official Canadian release, now superceded by the UK DVD)
Star Wars rental library edition VHS (picked up from a local video store that closed down)
That's what I can think of without being able to look right now. I don't actually own any laserdiscs.
--SKot