Hi,
The video being too far down the page might be an issue. I've seen this cause problems before, and in your case I think it could be a problem. More broadly though, I don't think you should have those videos on the category pages, because the video itself is just image slideshow and actually does more to hamper the using experience rather than help it. As rich snippets aren't common any more, I don't think you're going to get much value from having these videos on those pages.
Having the sitemap hosted at Wistia isn't a problem. You can point to a sitemap hosted on any site.
Other likely problems are duplicate content. You seem to have significant duplicate content issues as I'm seeing about 3 variations of that page indexed.
Hope that's useful,
Phil.