Pelosi and Schumer were waiting for their choreograhed lines to stand up and clap to, and they looked stupid because they messed up their timing to do so on key.
At least this year, Pelosi didn't rip the president's State of the Union address pages to shreds.

It's hilarious to me that they railed on Rep. Lauren Boebert and Rep. Marjorie Taylor-Green for their alleged uncivility. But nothing beatss the uncivility of Pelosi shredding Trump's SOTU speech itself during the Jan 2020 SOTU speech. And she spent pretty much the entire speech barely listening, and creating little tears in the pages to easily shred it at the very end right behind Trump. As petty and malicious as it gets

I'd agree that Boebert and Green were inappropriate to comment during the speech, they would have been better off to comment to reporters after the SOTU speech. Their comments during the speech could at least be interpreted as rude and inappropriate, and they were inaudible anyway, so their actions and comments required some explanation to even understand, that the liberal media will never provide. Better to make a complete comment in self-contained full context to reporters after the SOTU speech, rather than the questionably effectiveremarks they both made, basically heckling Biden during his SOTU address.