@5:57 that was a special train with grinding wheels to maintain the track profiles. In the next clip, the arcing between the overhead catenary and pantograph is caused by ice on the overhead catenary.
1:39 this is in the qiongzhou strait, china. This train ferry is mainly used to connect trains form mainland china to the island province of Hainan located in the southern sea, right below the mainland.
16:29 happened in utah. I remember when this happened. The FedEx truck was turning, but the roads were icy and slick, so they couldn't stop, and frontrunner runs on a VERY tight schedule.
5:55: there's nothing unusual about that. This equipment is grinding the rails to maintain optimum track geometry. (prevents derailments and excessive wear on both tracks and car wheels) It's supposed to look like that, and this work is typically performed at night.