Use the adjective bootleg to describe something that is sold illegally, usually because it was stolen in the first place. If you download a movie on your computer and then sell it to a friend, it's a bootleg film.
Bootleg is good for describing something that's stolen, smuggled, or pirated. You can use it as a verb, too, when you're talking about selling something illegal or obtained in a sneaky way, like secret recordings of a rock concert or contraband candy at summer camp. The word bootleg, which originally meant simply "the leg of a boot," refers to alcohol smugglers' trick of hiding flasks inside their boots.