Deuce, as we all know, in poker the context is everything, so sometimes playing something as speculative as 9 10 suited against an early raise may possibly be ok, though I would never play it. But in this particular case there was a lot of background, ie Negreanu had been streaming for a month, so opponents would know how he plays, ie he has very little respect for early raisers, tries to force them off hands, so they can trap him by playing strong hands passively, knowing that he will do their betting for them.
If he had been more alert during the series he would have seen this pattern, and realised it would mean players would be paying a very tight early position range, one that would be strong enough to call his all ins, so it would be better for him to try more to check down and hope his hand was strong enough to win, rather than going all in with pocket 8s or pocket 2s and hoping he will win a flip against a high card Ace. So basically, in this circumstance there is basically no way 9 10 suited would be ahead of the guy raising in early position, who in this hand had pocket KK, so a fold would have been a better option.
https://youtu.be/h9x7ouJbpjk?t=6590 is the hand in question, last hand on the stream, in the vid called 2020 WSOP Online $10,000 SUPER MILLION$ - Final 2020 WSOP Stream