YouTube is initially applying the captioning technology only to a few channels, most of them specializing in educational content. They include channels from universities like Stanford, Yale, Duke, Columbia and the Massachusetts Institute of Technology, PBS and National Geographic, and Google itself - its corporate videos will be captioned.
Companion website to a National Geographic special that explored subterranean NYC. Interesting, particularly in light of the current construction of the 2nd Ave. subway.
It's a secondary source and the information is fairly cursory, yet as it is organised around the different nations around the world it might be useful for preliminary or geographic research.