The benefit is for others as much as it is for yourself. Malware often has to be turned on. If you scan your files without opening or moving them first, you might be able to delete the bad files without causing any harm. And if the folder isn't shared that you download to, noone else will be uploading it from you, thus saving them from the grief of having to deal with the same malware.

Red files aren't being shared and black ones are. If you have done what I said they are not mixed in the library. shared folders will have black files and the files you have just downloaded will be red. If you want to be organized U can have videos and music by genre in different folders just sharing all of them.

It also isn't really nessesary to share all your files, because sharing too many files might get you in trouble. I try to stay under 1000 shared files normally. Much less chance of getting caught, than people who share several thousand files. I also try to share files that not everyone has allready, instead of things people can get from other easyly.

Hope this helped