I can't Believe they Just Fired a Flaming Orc from a Catapult!

I just finished watching In the Name of the King: A Dungeon Siege Tale and given that I went into the movie with very low expections (it's got a 3.8 on IMDB at the time of this writing) I actually kind of enjoyed it.

But seriously: How effective would you expect a flaming orc fired from a siege weapon against infantry to be? I mean honestly.