YT got me with a recommendation once again. Here's a high quality front-view video of a run from Hanoi to Hai Phong. Even without a reference point, the gauge seems narrow, not even 1067mm. Turns out Vietnam has 2,169km/1,348mi of meter gauge. The video seems to show some hunting oscillation, unless it's just how the camera was mounted or something. Also, this guy loves to blow the horn. As best as I can tell, he sounds it anywhere someone might emerge from the line side vegetation, although not at properly guarded crossings. Video by Mars Hartdegen.
https://en.wikipedia.org/wiki/Vietnam_Railways