I stumbled across this video my freshman year in college. Utterly amazing.
The best part of the clip (worth rewinding and watching several times) is the very first time you see Faith run across the screen with the little girl trying to get out of the way. If I was in a park and saw a two-legged dog running like a human, I would take off. The thought reminds me of a few notable scenes from Jurassic Park: the classic T-Rex jeep chase, and the dino herd scene...some of which has been recreated for you in the following video.
In all, this is a pretty amazing story. I have been unable to find out if Faith did make it into Harry Potter. If anyone can verify this, just post a comment. Have a good one!