"That long train ride" is a remix of a Half Life 2 soundtrack "Triage at dawn" made by DJ Dain. In fact i thought it was so awesome it deserves its own thread. Triage at dawn itself is only around 40 seconds long but contains such an awesome tune. This remix is full 5minutes long. I really made me think of Half life when hearing it.

Check it out:

I have it on my PC in my remix's folder along with about 20 MLP remix's

I remember a while back when people were saying this 'extended version' was from the leaked HL2 Beta (although as said in the OP, it isn't ). It really is rather nice, the original piece of music definitely needed the extension.

I know it. This is very good track. I really like the part after 0:26 ...