If the second youtube link gets deleted again, you can download it here:
http://kokayz.livejournal.com/562250.html 
Is there a reason why someone would go to a beach at night and cry?
Well, just imagine how you would react if you heard you have only 3 months left. Would you leave the doctor's office smiling from head to toe and going on like nothing happened?
Don't forget that Japanese people, especially men, have to act strong all the time and going to a beach at night to let all your emotions out you couldn't do during the day, doesn't seem that illogical to me.
Last summer someone I really love to death had to deal with the news that there would be a chance that he wouldn't survive his surgery and believe me, that news makes your world fall down.