These "new" CSX M426/M427 trains don't seem to be very long east of Worcester where P&W and/or Framingham traffic to/from Selkirk are picked-up and set-out. Eyeball observations show that train lengths east of Worcester generally run 30 to 70 cars, not including any Eimskip containers that are hauled on the weekends. Once B&E is up and running, I would guess it quite likely that EDPO/POED won't run east of Ayer with all or part of the consists being handled by M426/M427 east of Ayer. Just my opinion. But maybe in the future, CSX intends to fill out M426/M427 with domestic container traffic to/from Rigby?
So at this time, it would appear that this train 426/427 is the "one a day" handling whatever traffic originates in Maine.
Somehow, I don't think Chessie "got into this" if that was all the traffic that could potentially be handled. As she "purrs" away down at 500 Water, she has visions of Containers far beyond what this Icelandic maritime concern now gives her at Portland.
But back to the video, the apparently well-informed Narrator noted that the train was heavier than usual.