Amazingly fantastic! You know, if you sliced off about a half inch of that flat car deck on the front, you probably wouldn't see it in the video anymore. 
Yes, but then the car - or more correctly the sled - wouldn't work!

. It is really just a thin, folded strip of 0.02" styrene glued to floor ends/bolsters cut from an MDC box car. It took me maybe 15 minutes to build and another 15 minutes as I played around with bolster washers for the height eventually settling on letting the thing slide directly on the rails. The styrene comes in and out of view as the car flexes.

I had thought to mount a cut-off nose from an old CP Tuscan/Grey Atlas GP38 to the front so that the view was looking through the window, and I mocked this up, but I am not really inclined to put much more work into this. Right now it is for insert videos and an experiments .
But I do appreciate all the great comments. Maybe I will rethink further investment of time. The camera is great now I know how to use it...another tool for the arsenal.
As to the inside of the tunnel, nope, won't be further scenic'ing those! My 7 year old did suggest putting a Yeti inside it as a surprise - though I think Sasquatch is far more appropriate!
md