Thank you WyreNut for the response. So I think that the hotness of mine camera is not the problem. I already tried to leave it on for about 6 hours and its temperature is about the same after operating 1 hour.
I haven't tried the external microphone. I also plan to try it with the external microphone, but right now I don't have one, so I will try it later.
By the way, what the revision of your camera? A, B1, or B2? Oh, do you think we can use the Yahoo or Hotmail email account to receive the notice from this camera?