i'm looking for the best (and free) compression software. winzip and winrar barely save any space.

7-Zip have excellent compression rate.
Take a look at this site, where they compare lots of compression software: http://www.maximumcompression.com

As for WinZip I agree on that...but WinRar, using the *.rar extension??? I assume you are not trying to compress *.wav, mp3 or jpeg files...do you? That won't work you know

i'm trying to compress video files. i tried 7zip and it was the worse than ZIP and winrar. im starting to think video files aren't really compressable.

you can't compress files that are already compressed...so you can't compress video files...

oh ok, thanks.

Are there no 'uncompressed' video formats like wav for audio ?
Doesn't compressing wav using a data compressor instead of an audio compressor reduce the file size ?

Of course there is uncompressed video: raw RGB and YUV streams for example. And in that case using a data compressor will help, but, it makes the file unplayable and the gain is rather limited compared with most lossless codecs.

There is no gain in compressing a video file compressed with a lossy codec, as lossy codecs use additional lossless compression for more efficiency. At best you will compress the container structure and gain about 1%.

If data compressor isn't "multimedia-aware" it won't compress PCM audio data more than by about 10%. Most data compression algorithms (for text, executables, etc.) base on repeated patterns of data, and PCM audio isn't very repeatable. Most simple trick to make it more compressible is to transform the audio data in such a way that it won't represent values of particular samples, but changes (delta) between them.

never say never ....

The makers of the compression package Stuffit have written a program that can compress JPGs by roughly 30%. This isn't the raw image to JPG compression, this is lossless compression applied to the JPG file. Typical compression rates for JPGs are 2% to -1%.