Sometimes when a stage musical is adapted for screen, songs have to be cut to accomodate new material. This happened to several songs from Little Shop of Horrors, including Closed for Renovation, Mushnik and Son, and Ya Never Know.
In other cases, such as Covered Wagons, Open-Toes Shoes from Waiting for Guffman, a song is simply deemed superfluous, unnecessary, redundant, gratuitous, inessential, expendable, dispensable, unrequired and irrelevant.
In still other situations, a song might be cut for technical purposes. Once In Awhile from The Rocky Horror Picture Show was cut not because it was mediocre (as has been erroneously reported) but because filming was running behind schedule and the montage it was to accompany was incomplete.
On the other hand, sometimes the reasons for a cut are obvious.
If you don't recognize that, perhaps this snippet of a different song will help. Then again, perhaps not.
No points for guessing the movie, because I'm embarrassed by the fact that I like it so much.