Why doubleclick instead of single click?
Not sure if it is my browser or the game, but on the third slide, I'm not sure if it is interference with the browser or if there is no focus on the game to allow me to grab and move objects. (I'm using a rather current version of Chrome. I can interact with some objects with a single click. I double click and the "Prototype Studio" text in the Unity WebGL frame is grabbed.)
Is there a way to probably use something like user-select:none to prevent the frame's contents from being selected when double-clicking?