Hi
As far as I know there is no way to edit video in either Media Player or Quicktime.
Movie Maker is kind of limited in what it will do, If you are serious about editing video you will need to buy a video editing program.
I would recommend Adobe Premiere Elements.
You can download it and try it for 30 days for free.
I would recommend doing that to be sure that it will run on your computer anyway.
It takes a fairly fast computer to run it adequately.
Adobe - Adobe Premiere Elements : 30-day trial
It's what I use to make my videos.
It will let you do anything you want, crop the image, change speed while maintaining audio pitch etc.
While being pretty comprehensive it is still reasonably easy to use.
Here is one of my animated videos, with my character Lucy, the one below is 5 mb, as you see it but the original is over 300 mb, completely impractical as far as online use goes, but PE will let me save it in a lot of different sizes for different uses.
Here's a direct link...
I don't know what was going on with the other one, I've used ImageShack for years.
http://img132.imageshack.us/img132/3894/file6897.mp4
Mike
Ps. Premiere Element will let you select the size of frames saved from the video.