Anyone who downloaded the first developer release of OS X Lion from Apple (AAPL) last week had presumably signed a nondisclosure agreement promising not to breath a word of it (unless it was something Apple had already revealed on its website, its press release, or the demo Steve Jobs and Craig Federighi gave last September).

While the company can be brutal about enforcing NDAs, this one has been broken pretty brazenly. Screenshots and videos of Lion in action are popping up all over the net (and, in some cases, being removed under threat of legal action).

Of all the videos we’ve seen, the hands-on preview posted Monday by Engadget‘s Nilay Patel offers the quickest and broadest overview. Not being under NDA, I thought I’d grab a copy before it disappears.

My iOS-unfriendly vodpod version is pasted below the fold. As of Tuesday morning, you could still see the original video at Engadget here.

[vodpod id=Video.5670682&w=425&h=350&fv=]

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Also on Fortune.com:

• iPhone: ‘The mother of all halos’
• Dooce was paid to switch to Droid
• CNBC’s anti-Apple crusader

[Follow Philip Elmer-DeWitt on Twitter @philiped]