Just watched your initial video on the desk setup. Excellent point in this one adding the brackets to secure the counter tops. Will be duplicating your desk setup in my apartment using your links. Hope you get some $ off of it. You have a new sub sir.
It is drywall but due to the weight, you'll definitely have to use a stud finder and anchor the brackets into studs. That or find some legs that are rated for a lot of weight.
