It is a homemade tofu/jelly made with acorns. I gather acorns every year just to make it, a real seasonal treat.
The lady in the video says it has no taste but that isn’t true, it has a lovely nutty flavor and is so good. Once you’ve had it you’ll want it again and again. 
It really soaks up other flavors as well.
Sometimes I add chopped toasted peanuts to the jelly before it cools.
To make it from fresh acorns you have to soak with some baking soda, discard the water, blanch several times discarding the water, then roast and grind to flour.
Or you can just buy the powder: http://goo.gl/56ThgU
