Interesting concept....
.....but why not do them yourself?
Starting with the briefs that I give regularly I have taken a standard company template and re-worked the paper briefs into powerpoint presentations.
Not only does it give you a tremendous sense of achievement and satisfaction, but it also ensures that you compile the brief as you want it, the diagrams that you want, and once you get proficient at using the software you can animate the slides yourself.
Job jobbed.