An example: You have audio inside a composition. The audio is perfectly in sync if it starts at 00:00 where also the video start. When playing back from any other time, such as 20 seconds seconds into the timeline, the audio is not in sync.
Even though mp3 playback is possible in WATCHOUT it is not actually supported and should not be used.
From version 6.2, WATCHOUT supports Windows Audio Session API (WASAPI) and Audio Stream Input/Output (ASIO) protocol, up to 24 output channels. This feature offers individual channel volume and routing.