When a player is familiar with Gnubg he/she will just as i used to left-click on the cube to accept and right-click to reject the the cube.
like it that way as when you have completed your move and click on the dice and you opponent offers the cube you just have to click instead of going almost to the top of the screen
Comparing the buttons
GG Resign / reject / Undo / Accept
Ggnubg Accept / reject / Double / Undo
I'm Always puzzling to click on the correct button
Maybe you can add the click on the cube and to me the logic how gnubg put the buttons more sense
About the video I don't think that they will be viewed often maybe more when there are sometimes replaced by other youtube backgammon things