The highlight starts at 0:53:
Interviewer: And, Michael, I understand you used [Rosetta Stone] to learn a little Mandarin to prepare yourself in Beijing. How did it go?That's getting dangerously close to saying, "I didn't really learn anything so please don't ask me to say anything in Chinese." (But, then again, as Rosetta Stone is an advertiser on Fox, I suppose he didn't really need to worry about getting grilled by the interviewer.)
Phelps: Uh, it's a very tough language.
Phelps: Um, you know, uh, um, foreign languages have always been very tough for me to learn, but, you know, I figured I might as well, um, I'm gonna give it a shot and, uh, try it and, uh, learned a few of the simple terms and, and the masculine and feminine term, feminine terms, so…And to think that for years everyone's been running around thinking that Chinese didn't have any grammatical genders.
Oh, right. It doesn't.
Now go to the video and watch Rosetta Stone's CEO Tom Adams' face when Phelps drops the gender thing. I'm not completely sure, but I get the feeling based on the way his expression changed that he realized right then and there what was wrong with what had just come out of his spokesman's mouth.
So how did Michael Phelps come to learn about Chinese's non-existant grammatical genders?