"Existentialism on Prom Night" by Straylight Run was my favorite song when I was 17, even before I discovered the music video, set on a subway (PATH, which runs between New York and New Jersey). The use of transit in the video is particularly interesting. A lot of videos, especially for R&B artists, play up the gritty-urban aspect of the subway, featuring skylines and graffiti. They're often underground as well.
Meanwhile, the train in "Existentialism" flies over the landscape as sunlight pours through the windows. The car is very clean and the passengers are all minding their own business, save for the little girl dancing in the aisle. That's part of the video - everyone seems disinterested at first, but they're all mouthing (or signing) the words to the song until, eventually, a sort of dance party/dream sequence breaks out and they come together.
The song is very positive and idealistic (given the title), and it lends these qualities to the train ride portrayed in the video. It certainly wasn't intended as an advertisement for public transit, but it's very effective as one.