Nitpick, but it bothers me: The human factors of their demo video don't stack up.

Horizontal dragging with a mouse is actually really hard. Nobody's going to use it like that.

Your arm can easily move your hand and cursor up/down by pivoting your shoulder, but there's no mechanism for left/right movement. It's always an arc.

Or put another way: selection will be a lot slower and more tedious than the demo.