Fair enough, it's just something to check out, it's not meant to start a huge debate/war and get all religious about, burning in speakers or headphones doesn't really harm anyone or waste any time so it doesn't matter much if it's done or not, it's like choosing to mix naked........do it if it makes you feel better.
But if you check out the whole video you'd have to agree with the part where he says rather get headphones/speakers that are good from the start, if they're flawed then burning them in isn't going to help much, and if they're already good then they're already good pre-burn in.