Hope you can tell what's going on. I am pushing down with my hand opposite to the side of my heel on the wheel. Eventually, the wheel will go down past the horizontal level and the bead should slip right on the rim as long as you sandwich the bead between your heel and the rim. The reason why it need to be a raised surface is to use the edge as a fulcrum to get some leverage on the stubborn bead.

Stairs work great for this!