L looked at the video, and nowhere did I see them check the tyre pressures or the trailer lights, or have the assistant physically get out whilst the rig was reversing, except until right near the end. OK - he probably had tyre pressure monitors, but for the rest, ????
HI ..
An interesting vid of setting up a 5th wheeler ... And not a checklist in sight.
https://www.youtube.com/watch?v=0K25Cd3yZKU