https://www.youtube.com/watch?v=TMIepNv28C0
TheEllenShow: Thanks to IGT, Ellen has new slot machines in Las Vegas. To celebrate, she surprised gamblers playing her slots... and gave them a little bit of luck at the MGM Grand.
Ellen slot machines are in all the MGM Resorts casinos in Vegas.
In other words, this is fully controlled by MGM Resorts, the owner of Mandalay Bay.
which means she gets a percentage off what the machine makes each day (and so are tighter to make the revenue)