Depends on what "rare" means. Any officially released LD, VHS or DVD can be hardly rare since these are released in big quantities. Unless it is deleted shortly after the release and withdrawn from the market for some reason. If "rare" means that there is almost zero chance to find another copy of the same thing, then my rarest video is the promo VHS Making of Alien 3 obtained personally from the director. It is a working copy with a time counter running on the edge of the picture.

Otherwise, people from America could love some European or Japanese releases just because they cannot buy these so easy and vice versa. For example, Alien fans love the well-known VHS boxset called "the facehugger box". It was released in the UK in 1993 and if you live there, it is no rare item from your point of view. If you live in another country, you can still buy it through eBay, but you must spend a lots of money because it is pretty heavy and the postage fee is enormously high.