I have been working hard recently while learning Short Form 3 for my Kenpo green belt grading, due in about four weeks time. YouTube is proving to be a great resource for me, as it seems to be packed full of Kenpo videos on various techniques and forms, an excellent source of reference material.
Josh Ryer's "On the Mat" series in particular is well shot and staged, with clear discussion and demonstrations of the techniques and forms. Here is a video of Josh explaining Short Form 3:
"On the Mat 27 - Short Form Three" - http://www.youtube.com/watch?v=uZiKD597qvU
You can find the rest of Josh's videos here:
"True2Kenpo" - http://www.youtube.com/user/True2Kenpo
I also found this video of "Huk" Planas performing Short Form 3:
"Mr. Planas Kenpo Short Form 3" - http://www.youtube.com/watch?v=fhvmf5RL4S4
Updated 2021 : note that the above post was originally published in 2007, but is left here for archival purposes. Sadly those videos are no longer available, so I had to unlink them.