The problem I see with "passwords","registrations" etc, is then your work will get less exposure.
I personally avoid many sites that require a bunch of crap to view or use it. Such in filling out countless pages of registration just to use the site. Same would go for having to wait on a download, then giving out your email address then wait for a special link, to log on to just to get a password, too much wasted time and a turn off, thus creating a negitive feeling towards other work by the same person.
I disagree with piracy 100%, but must admit you make something and lable it "freeware, selectware, shareware, whatever" put it on the web and it will be used for free.
If it is a program that requires a fee, it will be hacked, cracked, patched etc.
You invite theft as soon as you put anything on the web.
I know that instances such as this might make some designers quit doing what they love too do, and that is a sad thought because they offer so much for us who don't know how to do it, but they must remember that there is another designer out there waiting to take their place if they ever do decide to quit.
About the only legal way I can see you preventing others from stealing your work would be to make it "payware" sure maybe not as many people will use it but you might be surprised by the amount that will. But again there is no possible way to prevent it from being stolen whatsoever.
I know how we could foil FSPirate, how about everyone here all go over there right now and start multiple downloads all at the same time and suck the bandwidth out of the sucker? ;D
