Not new, there are also some reports and complains like that few months ago.
I didn't know on how it happened but whenever you guys an exchange like IDEX, use it with metamask.
The guy on the video said there's someone who's using a remote access on the idex network, probably its his wallet and got his private key.
IDEX is a decentralized exchange so how it can be controlled by someone, unless he accessed the wallet itself.
I am aware of the phishing links; if that is the reason why these people lost their funds it wouldn't be as bad as if there is actually a private key sniffing issue as they mentioned.
That's my guess that someone stole his private key.
The scammer/hacker got $94,000 = 222 ETH and that's a lot. I'll take this as a warning and will be more careful from my trades there.