When the Engine in the first video dropped its load, ...
The reason is that the MTH coupler failed after pulling 9 heavy metal passenger coaches around an O-72 curve. Naturally the scratch-built full metal tinplate coaches are much heavier than the plastic-mold Rivarossi/Lima coaches. The heavy weight prevents the coaches from derailment when doing rounds 8 hours uninterrupted and continuously in one regular public exposition day. The European engines are made of Rivarossi/Lima bodyshell and MTH underframe+motorization. So, I have learned from this mechanical failure and from now on I let my engines pull only 5 or max. 7 coaches.