Ccleaner drive wiper!

What does this do exactly? Will this get rid of all the free space that's on my C drive? or will it totally just wipe it all except the important windows files and leave me with like 451/452GB on my drive..can someone please make a video of the Free Disk drive wiper?

a tutorial

and more. :)

Video..and I've read that already.

I think it would be more interesting to see a video of paint drying ! !