The video isn't working for me but I understand the issue. I've actually had this same problem and it actually tends to return every so often. A good cue for yourself is try to let your feet land underneath the bar. If it's an issue with bringing your feet up too early, and you're kind of "hanging" in the air, then try thinking of pushing through the ground longer on the extension.
Some drills to help this would be some hang snatches without bringing your feet off of the ground. So start in your receiving position, go through the movement and get used to keeping your feet down with little movement. Also, I would try some dip snatches and tall snatches as a warm-up before you snatch.