I don't see any problem if it is being used on a MUT, sidewalk, path, etc. Off-Road??? Not smart!!!
It looks like it attaches securely and has straps to keep the to keep the little piggies
away from the front wheel.
I watched the video. I didn't like them removing the stem for installation. Video showed the person reinstalling the top cap but not tightening the stem bolts. Someone is gonna mess that up.
Also, the guy riding in the video looks like he is having issues with the child being a little too tall. At times, he looks like he is sitting too high or has trouble seeing over the child's helmet when looking down in front of him.
Overall, I think it is harmless if used for just tooling around. It's far better than the iBert
or other types that position the child on the bars or in front.