Our experience is we've found a few sites renting our stuff that they bought either at retail or from our distributor.

Even though our DVDs say right on the back that they are not licensed for rental use, commercial exhibition, etc., the rental companies haven't been very accommodating when we've tried to discuss with them, and it's one of those things where, so far at least, it hasn't been worth the hassle for us to go after them.

Apparently Bryan Kocis at Cobra was venomous about such things and aggressively went after anyone using his content in video booths or rental programs and so forth and vigorously threatened to sue them into oblivion... which had the not-surprising effect of simply getting the threatened stores to drop his titles entirely. Probably not the wisest move.