The second showing had begun at 5:25. And there had been a 1/2 hour (30 minutes) break before it. So we substract this break from 5:25 and we get 4:55 - the time when the first showing had ended.
So the first showing had begun at 2:30 and had ended at 4:55. By substracting 2:30 from 4:55 we get 2:25 - that's the duration of the video.
