For anyone curious this video was filmed in a Dutch ICMm-model intercity passenger train, identifiable by the single-floor design, overhead baggage racks, seating arrangement and seat types!
Also known as the "Koploper ('head-walker')", these trains have been in service since 1977 and are a well-known staple of the Dutch landscape today. Pictured on the right beside a more internationally typical long-distance train, these trains earned their nickname from their unique ability to connect the heads of multiple separate trains together into one long train through a foldable hallway that could pop out from behind the large doors on the front, allowing passengers and conductors to cross between different units en-route instead of having to switch units during stops.
Back in the day this feature particularly benefitted the snack carts that would be brought through the aisle while underway, allowing a single cart to access the full extent of the train and thus eliminating the need to carry a cart for each set in a train, or transfer the cart between train sets during stops.
As this service became discontinued however the extensive maintenance– and reliability issues that plagued this system became much harder to justify, leading to the eventual discontinuation and eventual outright removal of this feature starting in 2005.
Though the ICMm has finally received its successor in the form of the ICNG (pictured below) its end of life is still not yet here, and it will continue its tenure as one of the longest serving models for at least another number of years more!
Bonus fact: Like the ICMm "Koploper", this train too has gotten its own nickname through colloquial consensus! Drawing from its still relatively sturdy head and the emphasis on the driver's cabin window through the use of black paint, it has become known as the "Wesp ('Wasp'!)".