Kick him in the nuts. Or find some effect that has a way that you can plan for his intrusion. Make up some effect that is destant for him to fail any way HA, or practice in a way that you can be prepared for any situation. It is a very good practicing tool to bust your own magic in a way that a spectator would so that you can be prepared to counter if it does hapen. Or if all else fails get pissy and turn the rest of the spectators against them. Not as in a mob, no no no don't do that but talk from another spectators veiw describing how they would want to see the effect with out some idiot wrecking everything. Personally he has to be the biggest (not trying to be mean because I don't know him) loser to go and download things to bring down another person, thats low. Anyways hope I helped, magicians will always have to deal with heacklers.