These first three videos are not specifically about fox walking. This interview with Tom Brown Jr provides the philosophy behind the way of life that uses fox walking as the normal kind of walking. Not much on production quality, the content of these videos is priceless. Most useful if you've been to one of his classes; much better than trying to read my notes.
Video quality much better in these two videos, one of which explicitly demonstrates fox walking. However, many details are left out, which is ok, since the two main points about how to do this walk are covered.
If you search youtube for "fox walking," you will find quite a few more videos, some I'm sure are excellent. If you find one you think is really outstanding, please mention it in a comment.