This may be wrong forum for this question - forgive me

I've seen a website that invites users to enter text, and the website takes that text and displays it in a movie within a PowerPoint presentation. Users can then download their presentation that includes their own text. For example, I entered "doughnuts", "are", "good" as my text, and this website chugged away and produced a PowerPoint presentation for me to download that displayed a video of a generic stickman juggling the three words I supplied.

How did they do that?

My guess: a form sends the three pieces of text to Flash (I don't know Flash) that somehow creates a movie that includes my text, and then there is code (written in .NET [it is Microsoft PowerPoint]??) that inserts said movie into a PowerPoint presentation.

Is that how they did it? If you wanted to create a service that offered users the ability to supply three words that were incorporated into a video that was, itself, inserted into a PowerPoint presentation, how would you do it?

Muchas gracias!