I've had this Rower for about half a year now (at least weekly use), but I've never had this problem before. Once or twice the belt has jumped out of the upper pulley when I was rowing at an angle (e.g. when I reached for my mobile phone to control the music). However, this can be remedied quickly (no comparison to the chaos in the video) and prevented by taking care not to row at an angle.

My machine has also arrived, and I can see this being a problem eventually. Either by incorrectly assembling the bungee cable (this is how the retention mechanism is referred to in the documentation) or by the loosening / stretching of the cable over time. The latter can be fixed by replacing it. It is also possible to build a guide around the belt from cardboard or plastic, if one is a DIYer.

Also, why the downvote, potential buyers of a thousand plus Franc product are not interested if it has an inherent design flaw?!