Butleg (an accent in Russian on "e") is an illegal music record from the point of view of copyright, usually made on a dictaphone during a concert. The English word bootleg is translated as the "upper part of the boot". It was in these places that smugglers of the early XIX century hid their customs from the customs. In a broader sense, a bootleg can be called any product that is released without respect for copyrights.
In an era when there was no Internet, licensed discs were quite expensive, so illegal recordings from concerts were very popular. In addition, on bootlegs you could hear the rare songs of many musicians. These things, played at concerts, were either not recorded in the studio yet, or were not even planned for release on official albums.