Differentiation of speed:
In this clip, we have a full view of a city through one of the train windows until another train running in the opposite direction cuts in, yet even through the windows of the other passing train, we can still catch glimpses of the city beyond.
Framing:
In this clip from Choi Hung station, framed by the glass and walls of the current platform, we catch a view of a departing train with one degree of separation, one platform away.
This station is unique in several ways: one, its distinctive rainbow patterns; and two, its parallel platform. Typically we see the train from the platform directly alongside it, yet here we see a train departing from one platform away. (11) The degree of separation gives us the impression that we are viewing it from afar, as if we are removed from the scene when in fact it is unfurling before us. Only the glass can afford such a glimpse; had the stations been traditional walls instead, this view would not have been possible.
Unexpected Location:
A clip taken from within an elevator, one can see the the gears and mechanisms through the glass walls.
Moving camera, static subject:
In this clip from Choi Hung station, we can see the station walls; the features of the station are visible through their reflections off of both the glass of the advertisements and the sheen of the colored panels sandwiched between each one.
Static camera, moving subject:
In this clip, as the glass doors close, we watch a train leave, revealing the bright glowing advertisements from the platform instead of from the train that had just left the station.
You have chosen a very interesting topic on glass and how objects are viewed through it. I think there is a lot of potential in the aspects and points you have raised but you can begin to develop the visual and aesthetic impact. Other than just recording the subject matter, treat them like the protagonist of your clips. It can be the label sign in Differentiation of Speed with the passing trains behind, or a person standing before the glass elevator.