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.
Yes, you right if we want to use IDEX or any other exchange site and we can use metamask as secondary security of our wallet then use it, because using metamask your wallet is safe while connecting in any exchange sites to buy and sell altcoins.