You need to see Thursday's episode to be able to understand this.
Similarly to how episode two's file size was far more than the first, the episode has a dramatically lower file size than the previous episode. This is because this time there is only one MP3 sound (i.e. songs from the audio portal), which add to the file size enormously.
This is slightly shorter than the first episode, although about as much happens in this episode as the previous one.