Muscovski is the man who works in the laundromat in Broker. At least, that is what he is called by Vlad ("Muscovski jerk"). When Niko went to collect Vlad's money, he ran outside the shop but was followed and pulled over by Niko. He said he would give Vlad his money, but was having trouble getting it together. If he gave the money to Vlad before he was killed or kept his money after he was killed, it is unknown.
It should be noted that like a typical pedestrian in GTA IV, Muscovski's appearance will be different in each of his appearances, not just with his outfit, but also his facial features, lacking or featuring of a mustache, and sporting different eyebrows and hair design. In general, Muscovski can be described as a middle-age man with a plump appearance. His name means "Moscow's" in Russian. So it's look like Vlad called him just "jerk from Moscow".