As someone who's taught for over twenty years, I've learned to admire and appreciate the different approaches of others.
Rather than focusing on the 'right' way to teach something, I prefer to ackolwedge that I am not, in fact, an expert, but rather, a student myself. For that reason, I am always eager to 'talk shop' with others in the hopes of garnering a new approach or insight. For this reason, I feel I am a far better teacher today than I was 20 years ago.
I enjoy Mangini's videos—I am not a drummer, but his passion and methodology transcends his instrument.
Not sure why anyone would want to tear apart an accomplished teacher's approach—I'd rather 'listen' and learn something myself...but that's just me