Jonny Philipps from I Didn’t Know That from the National Geographic channel demonstrates the true character of quicksand, and how to get out of it.
From doing a bit of research, quicksand seems to have quite a few natures, depending on how saturated it is, the fineness of the sand, and how deep and extensive it is. Here are two other videos that show some other kinds of quicksand.
The one above I’m guessing isn’t true quicksand, since quicksand tends to suck you in and resembles mud more than anything else. This seems to be more a Newtonian fluid like corn starch and water where the sand is simply super saturated rather than typical quicksand.