This must be an old video. The Steem type description videos have been done. Steem most likely pegs payouts to the USD so that you know exactly how much you will get paid in USD. If you earn $100 then when the payout cimed you simoly get the equivalent in steem. Not a scam, very logical. That way if the value of Steem bounces around you dont have to guess the value. It also makes the Steem Power more stable.