LOL. I had seen this, but it is great. again just shows how good they are if it is on a smooth surface.
Any pavement irregularities and not so much.

I have been playing with a modified roller bag wheelset and a Burley Travoy
Not keepers, yet , but the set ups offer a feel for what I need before deciding on what works best for me.
Needs to be wide , solid and ability to get up steps and pavement heaves.
Roller Bags do that at similar weight and balance and convenience