If your first reaction is "How the heck does it do that?"- it's a good question. The short answer is SMC takes loops and looping to another level by using "Themes". Themes appear to be folders filled with different, although similar and associated loops and as you make choices in regards to style, content and such of your music by selecting "Variations" SMC chooses and combines the appropriate loops. Change your mind or pick another Variation and it will alter the mix, swap a few loops and reshuffle the arrangement of them all. So it's important to realise that SMC doesn't "generate" music like a PC might generate a random, different series of numbers on every occasion- the same settings will give you the same music each time. It comes with a range of Themes and like any loop library there's a finite number of combinations you'll like and some you'll never use. The idea seems to be selling and releasing further Themes Collections later- again like loops.
For a very quick and easy way to create shorter filmscores (long projects simply invite more repetition) SMC works well- if for no other fact than its ability to make music exactly the right length to suit your video footage. There are separate tracks for adding voice overs and "transitional" music as well, with basic editing functions to shift everything around. Quality of the music is kind of "loopy"... you won't be doing James Horner's "Titanic" here. But for quick results when your client isn't Paul McCartney or some other discerning musician, SMC is a clever bit of software. A handy tool.