Literal Music Videos involve selecting a popular music video and adding in a dubbed-over audio track and subtitles, in order to literally describe what's happening in the video.
The trend began with the submission of a literal translation of Take on Me by film-maker/musician Dustin Mclean to funnyordie.com. Despite Mclean making only four of these videos, they recieved attention on social news sites like Reddit and Digg. A trend eventually began, with other users submitting their own literal videos.
Not to be confused with Phonetic Translations, which idolizes parody and alternate lyrics as well, but with subtitles that replace the lyrics with what they sounds like.