The stream they think has been hacked is the one reading the cards that the booth can see. It has been done before…

Might as well note that often the announcers mikes are wireless, the transmission of the broadcast is TV but the booth/producer is UHF in many cases, who knows if the camera crew isn't being directed with inadvertent details. Finally, who runs the graphics that show the percentages for the hands. There are so many potential holes in the system, that some fairly smart electronics person could find something as useful as the actual card cameras.

Maybe Adelstein has a terrible and obvious tell?

The show is investigating and says they will publish the findings whatever they are.

My favorite part: “Essentially she played a very bad hand in a way that suggested she could see her opponent’s hole cards,” said poker pro Matt Berkey, who runs a well-known poker coaching academy. “Her hand was so bad that the worst player in the world wouldn’t want to put any money into the pot.”

Yeah that's reason people are suspicious, not as she claimed, because she's a woman poker player.