@TD: That is one opinion off course, none of which has been tested in court. High crimes and misdemeanors did have a meaning at the framing of the constitution. If you're an originalist, then you'd interpret it as such.
High crimes - activity by or against those who have special duties acquired by taking an oath of office that are not shared with common persons
Misdemeanors - a less serious offense than a felony
This was intended to show that the presidency was to be held above reproach from any criminal wrongdoing, including non-felonious conduct.
The question is whether the President did anything wrong, and it will be very hard to prove the President did so. He told people to "peacefully protest" which is legal. He's not responsible for the mob peacefully protesting within the building, as much as Bernie Sanders was not responsible for the guy trying to shoot people of congress a few years ago after he said "they're trying to kill your grandmother". If Trump is held responsible for this, so should Pelosi be responsible for it, she's the one that indicated her contempt for the plebes with the "let them eat ice cream" controversy, or the Squad is responsible for BLM protests this summer etc etc.