It’s easy for Apple (AAPL) aficionados to take umbrage at Ed Bott’s recent series on ZDNet about a piece of malware called Mac Defender.

After all, Bott has made a career writing books (more than two dozen), editing magazines (PC Computing and PC World) and writing columns about Microsoft (MSFT) Windows, a family of operating systems so riddled with viruses, worms, trojan horses and other infectious malware that without adequate protection they quickly become unusable.

So to write nine pieces in four weeks in Ed Bott’s Microsoft Report that issue alarms and warnings about “serious malware” coming to a system (Mac OS X) that doesn’t need antiviral protection might seem disingenuous. And indeed, he was neatly skewered early on by Daring Fireball‘s John Gruber, who trotted out a collection of similar dire warnings dating back to 2004. (See Apple malware: Six years of crying wolf.)

But Bott is actually doing Apple and its customers a favor.

He was among the first to warn Mac users of a fake antiviral program called MacDefender that is sufficiently serious that Apple felt obliged to issue instructions for how to deal with it and a system update to protect users from the early variants (there have been others, which Bott seems to learn about within hours of their release).

[Note: An earlier version of this story suggested that Bott was getting fed this information by sources in the anti-virus business. In fact, he says, the information flows the other way. He wakes up at 4:30 a.m. every morning, searches sites he knows are poisoned, and reports his results.]

And now Bott has done his most useful service of all: He has posted a 2-minute YouTube video that shows MacGuard (the latest MacDefender variant) in action. If you see something like this on your screen, don’t panic. Quit your browser, download Apple’s support article and follow the instructions.

Below: Bott’s video (for best results, play in fullscreen mode).

[youtube=http://www.youtube.com/watch?v=WoogO_f6DLI&feature=player_embedded]