Well, as the estimable Dr. Parker has been dwelling on Naihanchi, and as Openhand has offered a few words on the subject,, it's kind of on my mind. I thought that I would proffer up a bit of a tour as to the kata, at least in terms of various performances.
First, I should note that if there is up-to-date video anywhere on the web of any of the Naihanchi kata as they are being taught in RyuTe, I am unaware of it. Anyone seriously interested in learning about Naihanchi would do well, I think, to order the videos from the RyuTe Renmei. They will, as far as I know, sell them to anyone. You should be aware that the applications shown in those videos only scratch the surface. On the other hand, they should give you at least a little insight. You certainly won't find the money wasted.
That being said, here is video of (so I gather) a student of a former student of Taika Oyata performing Naihanchi Shodan.
There are, of course, about a bajillion different Shorin Ryu organizations out there. Here is a performance by Onaga Michiko:
Shotokan (Funakoshi Gichin):
Shotokan (Kanazawa Hirokazu):
Lastly, I have to include a version of Naihanchi Sandan, as this is, according to my own teacher, my best kata. I have to admit that I like it a lot. This version, of course, is not quite like the RyuTe version, but it should give you the flavor of the thing.
Well, that wasn't actually "lastly." I do have one additional thought for you. It's out of my own head and no one else should be blamed for it.
You know those cross-body "punches" you saw in the videos? Well, they can be things other than punches, of course, but the reality is that you can, in fact, smack the crap out of someone with one of those. I have hit the makiwara with them more than a few times, and boy howdy! Does it go!
What's more interesting yet is that if I change stances and hit the makiwara from any other position after having done it in horse stance, I find that the power in my punches is noticeably enhanced. I really do think that Naihanchi helps you learn to subtly recruit punching power from disparate parts of the body.
Just my two cents, of course.