There is no sound, as it was not yet programmed to record sound.
Note: Anything higher than 8x replay speed messes it up (since some frames are skipped at that speed). It is set back to 4x speed at 0:41.
Any speed you use in Starcraft will be played back at normal (fastest) speed in the video. This means that even if you lag or set it to slowest, the video will not. Or if you set it to 4x speed for example, the video will play back at fastest.