Every theorist will get things wrong at least once, but they will throw enough shits at the wall that some will eventually stick.
I remember he was rooting for Imu as the final villain for a long time, during the middle of the Elbaph flashback, he said 'this chapter sealed it for me who the final villain really are, Imu.', then the next video went 180 degrees says how we got things wrong and blackbeard is the final villain. That is one of the glaring one. I'm just saying and don't take it as a personal attack.
What did he gets right? I have bad memories, do you mind tell me some of them.