For Your Media Studies Staff/Students [Perhaps?] The Peanut Gallery [Google Chrome]
Link: The Peanut Gallery
To get started select a clip and say 'Action' When the clip is running speak the lines you want to add to the clip. When the clip has ended you can review the clip with your added text. I tried it at home but the added text wasn't very accurate [A bit noisy here: I think that confused Chrome]
Peanut Gallery is a Chrome Experiment that lets you add intertitles to old film clips using your voice, then share those clips with your friends. It uses your computer's microphone and the Web Speech API in Google Chrome to turn speech into text.