Derail pretty much has it.

Any electricity transmitted into the train body through the electrification system or through lightning strike is passed quickly to earth through the metal of the train body. That said the advice given to motorists if they find themselves in an electrical storm is not to touch any metal parts of the car, especially any that are bonded to the exterior, as these may cause an electric shock in the event that the car is struck by lightning.

In the video you refer to, the overhead power lines will have quickly tripped out due to the poor unfortunate causing an earth fault. This means that any danger posed to those inside or near the train would have been fleeting. They would have had to have been touching some metal part of the train attached to the outside to have felt any effect.