Trick for programs that don't support the masking feature!

[xPiikanyaa]

This works in any video editing program with a multiple track timeline and has the chroma keying effect. WARNING: Not for amateurs or lazy bums. (Yeah, I know I am a lazy bum and some people consider me an amateur, but still...)
You will need:
Image editing software
Video editing software with a multiple track timeline, such as Sony Vegas
Video clip/picture that you want to mask.

[xPiikanyaa]

STEP 1:
Take out all the frames from the clip you want to mask. I just slowed down the clip and saved a still image of each frame using Sony Vegas. (It all depends on the software you're using - I'm not sure how to do it in other programs.) I recommend using a short clip if you're lazy, since it does take a pretty long time.

[xPiikanyaa]

STEP 2:
Now comes the tricky part. Using the image editing software of your choice (I used Microsoft Paint), you'll need to paint out the background of every single frame, leaving only the part you want to mask. This is a long and tiring job, so I hope you didn't use a really long clip. Well, I did warn you. It's even harder if you have a clip with small shapes.

[xPiikanyaa]

STEP 3:
Once, you've got all the frames ready, insert them back into the timeline. Make sure you zoom right in on the timeline and shorten the time length as small as humanly possible. DO NOT INSERT THE FRAMES STRAIGHT BACK INTO YOUR AMV. IT WILL ONLY MAKE THINGS HARDER. Once you've done all that, render the video. Then put it in your AMV, and use the green-screen effect to get rid of the background. For this reason, I recommend using a background colour that isn't in the part that you want to mask.
Congratulations! You're all done! Now you can use the clip as many times as you want, and add any required effects to it when making AMVs.
Hope I helped!!!

[Bauzi]

In my experience I wouldn't suggest this method. If I have the chance than I would use alpha transparency instead of a keying colour. It will be more accurate. Some keying effects don't work that great.

The pen tool is avaible for everyone if you install GIMP. MSPaint is a bad option, because it will only cause much more work due to it's lack of functionality and a proper vector tool.

So.. you can use this method, but please use GIMP, Photoshop or something similar and read this guide:
http://www.animemusicvideos.org/guides/PenToolGuide.pdf
It's more than usefull to learn fast and accurate masking.