You can’t be unkind or discourteous to a video recording. That is like being afraid to hang up on those stupid campaign recordings because you don’t want to hurt someone’s feelings. It’s a freaking recording. There is no person there.
A real person deserves civil treatment (with a few exceptions). But I’ll be damned if I have to treat their flipping mechanical or digital proxy with respect.
The boo’s were a protest against the President sending a video instead of coming himself.
They would not have boo’ed him in person, since they invited him and they would have been pleased if he’d chosen to address them in person.