I'll take a guess and say the Dash-9 at the time you specify was a custom modification and paint scheme created for Neil Young's HORDE layout. Neil used to take this layout to concerts he put on I believe in the 1998-ish time frame. Note the large lens below the headlight is the camera used for the track level view. He even brought this layout to York once with a huge diamond-vision screen to show it off, it was quite impressive (you could see the track level view from halfway across the parking lot as the train moved! ).
The boxcars were probably similarly custom painted. There is a HORDE boxcar that was offered to the general public, but it looks nothing like the red cars behind the engine in the video. (It's a white base color with a HORDE graphic on it - I didn't watch the whole video to see if it showed up there)
The good news is, if you are willing to go for a more traditional paint job on the same engine, the GE Demo version that is seen around the 18:36 mark is available somewhat regularly. It's not by any means as well detailed as more recent versions of Lionel's Dash-9 (it was made in 1996-1997). It's number is 6-18226, with a similar Southern Pacific unit that is item number 6-18228(video).
(sorry if any of the above was covered in the audio, I was watching without sound )
18226 pic:
Hope this helps. Even nearly 20 years later, I still think the horn on these is one of the best I've ever heard on an o gauge engine.
-Dave