As I mentioned, I had seen the show's tryout in Chicago with my folks. And it was an utter joy, the audience laughing its collective pants off. The movie version of the musical is okay, and has some terrific things in it, but too often it's too flat and filled with odd things cut. Ultimately, the vibrancy and theatricality of the stage production is missing.
One example is in the number that Leo Bloom sings, "I Want to Be a Producer." The great fun of the number is that Leo, played here by Matthew Broderick, is at his job in the accountant's office, bored out of his skull, "So unhappy, so very very very unhappy," when he begins to fantasize about his dream, to be a Broadway producer. Little by little, his dream morphs into life. There was something particularly joyful seeing that happen before your eyes on stage -- and then returning into the boring office. The staging isn't so spectacular, just whimsical and well-blended. But that's what makes the number so fun. (By the way, you miss in the footage below a huge marquee that opens up in the black background after Leo sings that he wants to see his name in lights.)
In the film, they chose not to go for the sense of whimsy in the changeover. The problem is that a movie audience basically grasps the concept of cutting to another location and that everything isn't necessarily filmed in real time. So, the simple and clever morphing comes across as a bit heavy-handed and "so what"? If they could have made the transition more seamlessly, trying at least to replicate the whimsical sensibility of what they were trying to on stage, it might have retained that charm. It just...CUTS!!...into his fantasy, rather than blend it all together to overlap his unhappy life and fantasy.
But here's how it was done on stage. Again, nothing spectacular, very simple, in fact, just seamless, which helps make the joke. And as for the humor, it's all the more a treat to hear an audience laughing. And laughing.
(One thing I appreciate, too, is how the video continues past the conclusion of the song and includes my favorite part, "The Big Finish.")