He doesn't know. If his laptop is disrupting the network (almost 100% positive it is) by making Dota unplayable, as well as causing other roommates Netflix to stop playing by saturating the bandwidth it's going on the shit list.
I'm going to offer to clean his laptop to try to remove whatever rootkit/torrent virus he has on it now, but in the meantime QoS on the Laptop's MAC Address is the easiest solution.
fair enough, i guess
good luck though, shitty internet in combination with 2 or more bandwith hungry users under the same roof is never fun