I don't know about DVDs, but a quick search of "wushu double ax" yielded three forms very quickly. Substituting "kung fu" would probably have turned up a lot more. Have you checked there?
Sometimes videos on youtube are taken from a DVD, and the DVD is named in the description. That's what I was looking for anyway.
The other thing to consider is that the three videos I watched on youtube were all from different kung fu styles. So various styles might feature double ax forms. Double ax won't likely be a style in and of itself. So some more research might be required on the styles involved. Then you can look for DVDs on that particular style that include weapon work. Do you already have a kung fu background? I may be preaching to the choir here. My apologies if so.
I have a background in Wing Chun. I watched the different videos and of course noted the differences. I asked originally more out of curiosity but now, I'm going to keep digging. I wonder if there's an app for this?