The time Terry finish eating the snack is 8:30pm.
Here is the analyzation: He starts to watch the movie at 5:45pm, then after 2 hours and 20 minutes, that is around 8:05pm (7:45pm + 20 minutes = 8:05pm), THEN, the keyword here is then, which means, after he watches the movie. There is additional 25 minutes on the time, which is 8:30pm. Therefore, he finished eating the snack in 8:30pm.