He is saying the opposite. The downtown train arrives on the hour and the uptown train arrives at 5 minutes after the hour.
"The solution is that, even though the trains arrive with the same frequency, the downtown train departs just a few minutes after the uptown train has departed. Because of this, there is only a narrow time window in which the man is able to get on the uptown train."
s/after/before/ to fix the explanation.
>even though the trains arrive with the same frequency, the downtown train departs just a few minutes after the uptown train has departed. Because of this, there is only a narrow time window in which the man is able to get on the uptown train.
He should say it like you suggested though.