Lizzo started YouTube's Dear Class of 2020 online graduation event on Sunday by playing "Pomp and Circumstance" on her flute.She was accompanied by members of the New York Philharmonic orchestra, who appeared with her remotely via video.Other celebrities appearing during the event included Beyoncé, Lady Gaga, Michelle and Barack Obama, Katy Perry, and Justin Timberlake.Many students graduating in 2020 haven't been able to attend their graduation ceremonies because of the coronavirus pandemic.