To understand why this specific long-tail keyword exists, it is helpful to break down the user search behavior behind it:
What likely changed
: Represents "Dual Audio HD", a file encoding specification where the video contains multiple selectable audio tracks (such as the original Tamil alongside a Hindi or Telugu dubbed track).
Early releases of dubbed movies often have "theatrical" audio (recorded in a cinema). An updated link usually features Official Dubbed Audio with 5.1 surround sound.