"Later designs would allow the threshold to rise quickly to combat the wizard-goes-to-the-cinema problem. The WGTTC problem is where a machine has adjusted down to a low replay score because it is mostly played by novices. "
Pure speculation on my part, but I would hazard a guess that it's a call out to the song "Pinball Wizard" by The Who (https://en.wikipedia.org/wiki/Pinball_Wizard). Some pinball wizard goes to the movie theater where it's common to have a few arcade and pinball machines in the lobby and racks up an incredible high score that is unbeatable by your average movie-goer while waiting for popcorn. This discourages other customers from playing and the high score is adjusted down to encourage more play.
Many Cinemas/Multiplexes will have a a room full of video games (and previously some pinball machines). These will be mostly played by novices who are playing a game while they wait for their movie.
Since these novices are not very good the replay score will be automatically tuned down on those machines. Which causes a problem if a "Wizard" starts playing on them since he will easily reach the replay score. Thus the machines need to be programmed to react quickly to a sudden increase in player skill level.
The next sentence addresses that:
"Then anytime an above average player gets on the machine, he’s getting free games all day long."
Since the replay score is set based on the top percentage of scores, if the majority of players in the movie theater (novices) lower the average score, a good player (wizard) is more easily at the high end of the score distribution, earning free plays consistently.
a strange name though, how does a wizard going to a cinema reflect novices playing a pinball game?