Notice no one treats Biden this way. He's not had a tough or adversarial question for the entire campaign.
Good for Trump.
This is perhaps one of the most infuriating fallacies employed by conservatives: the idea that the media needs to treat every politician with equivalent shares of positive and critical coverage, regardless of individual merit. Donald Trump and Joe Biden do not have the same records or the same behaviors. If Joe Biden was refusing to acknowledge the results of an entirely legitimate election, the media would "treat Biden this way." But he isn't. The reason that Donald Trump has been one of the most intensely scrutinized politicians in American history by the media (aside from Fox and OAN) is because he is objectively the least honest; there is simply no comparison between Trump and Biden in this regard. If most of the noteworthy things you do are negative, most of the questions and coverage you get are going to be negative.
Also, how are the questions in the video remotely "tough"? They're asking about an extremely basic question that past presidents have never had an issue answering; actually, it's an extremely basic question that has never even needed to be asked before. It's only an issue because Trump is making it one.