1) How are you "uploading" the video? Are you copying the M2TS or MTS files from the camcorder to the computer with a USB cable or using an application to move the video files over?

1a) If you are just copying the files over USB, when you "try to watch the video" what are using for a media player?

1b) If you are using an application to move the files, which application?

2) When capturing the video, what "quality setting" is being used?

2a) When capturing the video, was digital zoom used?

2c) When capturing the video, how was the lighting environment? Daylight? Evening/night/low light? Indoors?

3) When capturing video, was the subject not moving much or fast action?

4) What computer hardware manufacturer and model number are you using?

5) When you "watch it on my camcorder everything is fine" is that on the camcorder's tiny LCD screen or when the camcorder is connected to a larger-screen HDTV with an HDMI cable?

There may be more questions...