It’s pronounced “meem,” and a lot of people online actually make fun of people who pronounce it “me-me.” So many people make fun of it, though, that some people have taken to pronouncing it “me-me” ironically. So if the gal on TV was younger, it’s possible she was pronouncing it incorrectly on purpose.
Can people just make up their own rules of pronunciation? Well, I guess so. Plenty of people give their kids names that phonetics rules say should be pronounced one way, but they pronounce it another. It’s their kid so….