Why is it so easy to resize the entire thing/change the entire resolution on the fly with very limited cpu/memory resources?

As an example, my creative zen vision m is limited to about 2-3mbps video (depending on the type of codec), but has no problem at all scaling to the exact required amount that's needed for either its screen or its output to my 576 line pal tv.

Is it calculated or could it possibly be done electronically (non-binary system used to blend/get the average values) or could it possibly be done optically as in mirrors/prism-style type of blending of lights? There obviously has to be something done to meld or blend the images....

And my next question is this: Suppose I have a 700x450 movie (or any movie that's not exactly the resolution of my tv). Would I do better to convert it to the exact, native resolution of my tv and do a double-pass on it or would it not matter?

And suppose you had a 700x450 image, and you wanted to resize it down to 320x200. Would it look far worse if you first resized it to 700x449, then 699x449 etc. or would it be the same as if you did it all in one go....?

I wouldn't really do this for all my movies, but I'm just deadly curious, you have no idea how curious about this. I'm thinking of learning everything about the MPEG or MPEG-2 language, just so I can see first hand how it works.... I know it would probably take a very long time but as we all know here, video and encoding are very important parts of life!!!!