tl;dw: It's hard to get SBF to admit to fraud involving Alameda because he can fall back on the excuse that he wasn't the CEO and didn't know what was happening (even though there's every chance he actually did). So the youtuber hit him with a more targeted question: if FTX guarantees deposits are not traded, why were deposits not able to be withdrawn -- where did they go? He gets SBF to admit that they were commingling regular deposits with funds from customers doing riskier things like margin trading, and during the run those riskier users withdrew funds that should have been deposits that were set aside in a separate pool. That exposed regular depositors to risk contrary to what was laid out in the TOS. SBF gets mad and lashes out.