I'm surprised and very glad that this had sound. Those old school Baldwins sounded great! Sort of like a cammed out Big Block V8...
If you looked at the direct YouTube page, you'll have seen the note that the sound was added after-the-fact from the poster's sound library. I suspected as much since this was obviously 8mm film and there were no consumer 8mm "with sound" cameras at the time.
But that said... !!!... he did a great job dubbing the sound. A much, much better job than, say, several releases of the Emery Gulash 16mm films of that era. Having heard Baldwins "in the wild", the audio was darned close if not spot on, especially the center-cabs. The tractor-like clatter is distinctive, and the effort to even address Doppler was impressive. Tip o' the hat to the YouTube contributor.