The longer version:
In addition to being the author of a whole bunch of cool screen savers, I was one of the founders of Netscape, the company that brought the first usable web browser to the general public, and I was also a founder of Mozilla.org, the organization that you know best for Firefox. I've been involved in the free software and open source community since the mid-80s.
In 1994, while chasing the tail-lights of Netscape's unprecedented success, Microsoft used their monopoly in one market -- operating systems -- to make competition with them impossible in a different market -- web browsers. Specifically, they used their operating system monopoly to drive the market price for web browsers to zero, instantaneously eliminating something like 60% of Netscape's revenue.
It's hard for any company to survive an injury like that. Netscape succumbed to its wounds three years later.
In 1999, The Department of Justice found Microsoft guilty of Anti-Trust violations, but by then it was far too late: the company that I helped create had already been killed.
Microsoft's lawyers also subpoenaed my personal email at one point, which I took specific offense to. So seriously, screw those guys.
Now, every now and then, someone ports some of my XScreenSaver code to Windows, usually because they don't realize my feelings on the subject. When that happens, I usually send them an email something like this:
I see that you're distributing a Windows port of my XScreenSaver program. I'd like to ask that you please stop.
Because of the license under which I released XScreenSaver, you are legally free to do whatever you want with it, so long as I am credited for my work. I put this license on my code because I believe in giving people the freedom to make their own decisions, rather than trying to force them to do the Right Thing.
But, I wish you wouldn't release any Windows ports.
This is because I despise Microsoft's business practices, and I would feel very bad if any of my work went towards making Microsoft more successful. A screensaver is a trivial thing, but if you like screensavers, then you believe your computer is improved by having them. So by porting my screensavers to Windows, you improve the Windows environment. Any improvement to Windows helps Microsoft. I do not want my work to be used to that end.
So though I cannot compel you, I am asking you -- please don't do that with my work.
I understand that you may not agree with my opinions, but I hope that you will respect my wishes anyway.
Usually they say, "Oh wow, I had no idea! Thanks for your 25 years of work on this!" and they do the right thing.
But sometimes, not. Sometimes they just don't care about ethics or the wishes of a creator. Some people have the sociopathic attitude that if it is legal to do something, then that also makes it right.
There's one guy in particular -- and I'm not going to link to his site, for obvious reasons -- but when I asked him to stop distributing my code, he started sending me porn. I'm not joking, he literally called me names and emailed me a bunch of porn images. It wasn't even good porn. So if you have any respect for my decades of work, you won't link to, advertise or otherwise promote that guy's code. I'm sure it's not very good anyway.
At one point he was even trying to sell it. You know, the thing I've been giving way for free for decades. I'm sure that went really well.
So, if you search around, you might be able to find someone's old, partial, halfassed, unauthorized port of XScreenSaver to Windows. Maybe more than one. If you're lucky, it might not be riddled with viruses. I ask that you -- please -- do not download it, do not link to it, and do not share if with your friends.