The reason this is so suspicious is the idea in poker that "you can't call a bluff with a bluff" - that is, even if you think someone is bluffing, you can't call them if you don't have "some kind" of hand yourself.
You can raise them, and try to get them to fold (even if you have nothing)... but you never call a bluff if you have nothing yourself.
She had about as close to nothing as you can get - one over card and very few drawing outs. You can see from the percentages she was actually behind (even though she had the high card).
This really means 1 of 3 things happened:
1. She cheated - I don't know anything about the game/setup - apparently it was live-streamed but I have to believe they have a tape delay otherwise cheating would be trivial. No idea if there were spectators in the room, etc...
2. She misread her hand (thought she had a 3 for example). This happens more often than you would believe, even for experienced players.
3. She just made a bad call. I don't know anything about her, and crazier things have happened even if high stakes poker, but usually top players avoid calling with such a poor hand and poor outs.
Odds are it's probably #2 or #3, but I can understand why the other player would immediately jump to #1.
(also, for what it's worth, he really wasn't bluffing - it was a semi-bluff - that is, he hadn't made his hand yet, but he had a LOT of outs and was 50% to win against a huge number of possible hands.. thus a bet to take the pot was probably the right move to make).