The idea of doing an entire show in two minutes came from Marc Kenig who, I believe, got it from the NY G&S group. In their version, you take all the lines with personal pronouns and emphasize them: We are gentlemen of Japan, I am the captain of the Pinafore, We are dainty little fairies. Anyway, I put one together and it caught on, and I've been doing them ever since. In my version, I try to take what's essential to a song or piece of dialogue and present that. Then I have a bit of fun with it, and get input. And in my theater groups, the techies perform these parodies; heck, they don't get the applause, and this way they get some recognition (at least, they do if I introduce them). Note that you don't linger. You march right through it.
WARNING: If you're not familiar with G&S, these things probably won't seem very funny to you. But if you're at a party after a closing show, and you're kind of tired and a little punch drunk from the intensity of recent weeks, these are screamingly funny.