Interesting. I just tried to replicate what you did in the video and the top can does not spin at all. I wonder if I have an older/newer version. Thanks for the video.
I have used them for years and mine will not do this. My guess after looking at the video (can't see for certain) is that we are using them differently. I tighten both handles separately, like you would a lock nut. I torque the first one until it cannot turn, then tighten the second one until it cannot make another half rotation. Then I add the next 'stack' in my old truck I ran a stack of four - laying flat. I kept them very tight and they never rotated and when I forgot the keys I could not get them off. I kniw they have changed the design over the years because I had hardware that did not work with my newest gas can without rubbing.