Here's another article about a Native American language that is at risk. However, one Native American, Marie Wilcox, is determined to keep it going. She has documented the language in a dictionary that is the "longest work of its kind," though I'm not sure what "kind" it is.
Judging by the article he links to, I think he's saying that speakers of these languages have unparalleled knowledge of the natural world, and we have to find out what that knowledge is before they die. The languages themselves don't encode unparalleled knowledge of the natural world, at least he provides no evidence that they do.
I didn't get that from the article. I think he was just saying that we are losing a bit of culture when languages are lost. And we are, aren't we? Wouldn't life be a lot less interesting if we all had one language?