I understand this discussion to have been about the 13 Posture form listed on this website, yes.
This form was created, as I understand it and I might be wrong, by Grand Master Yang Zhen Duo. I don't believe I've ever seen a video or DVD of this form made by either the GM or by Master Yang Jun. There may be, but I've never seen or heard of it if there is.
There is, however, a video of this form. It was made by Han Hoong Wang, Disciple of our Grand Master, Yang Zhen Duo.
The video was made available to my class by Bill Wojasinski, Center Director of the Louisville Yang Cheng Fu Center, when he taught us this form but I don't know any other way to get ahold of it.
I just visited Han Hoon Wang's website, www.michigantaichi.com,
and I don't see a "products" section or anything like that where you can order it. Maybe I am missing it though. She has her e-mail address posted there, you could ask her directly how to obtain the video.
It is an excellent, excellent video. She is very easy to follow and her forms are flawless. I hope one day to get up to Michigan and at least observe one of her classes.
I made the mistake of packing my Han Hoon Wang videos away when I started renovations on my house, I have her videos of Section 1, Section 2 and Section 3 of the long form as well as the 13 Posture form, and I've sorely missed them for a few months now. Since they are in my storage unit, in a box on the very, very bottom of the pile (of course) I haven't been able to retrieve them yet.
When I want to eek a more accurate performance of the 13 Posture form now, I have found that most of it is from Section 2 of the Yang long form, and so I am able to use Master Yang Juns absolutely amazing DVD of the 103 Posture long form to get the details I am looking for by just viewing the relevant posture from there.
Anyway, I hope this was helpful to you in answering your question.