Can someone explain these settings.

Can someone explain difference in these settings

1. letterbox
2. 4.3
3. 16.9
4. pan and scan

4.3 is what you would consider normal screen aspect as opposed to 16.9 which is widescreen.
Letterboxing is a way of showing widescreen on a 4.3 aspect ratio screen that preserves the entire picture.
http://hkfanatic.com/widescreen/lett..._ex1_after.jpg
as opposed to pan and scanning in which again a widescreen image is shown in 4.3 aspect but part of the original image is lost allow the picture to fill the screen.

http://www.high-techproductions.com/widescreen2.jpg
To ensure that the most important part of the scene is not lost the image will seem to move from side to side(pan) as needed

Are all widescreen movies suppose to be same settings, because when you download a avi movie there all different heights. Downloaded one other day and its got a wide green strip on the bottom so guess be downloading it again.

For perhaps too much information, check out doom9.net. There is a heading under guides entitled "Aspect rations explained."

ty heading there now