Topchair inventor shown in video climbing stairs to Eiffel Tower

I saw this video showing the Topchair, which is being sold in France and marketed in other countries. The inventor is shown climbing the stairs on his way to the Eiffel Tower....very cool. It appears there is a tractor-tread underneath the chair which grabs the edges of the steps as the chair descends - and the drive wheels (and other wheels) lift out of the way and/or support the descent....