I wasn't really a fan of Joe in this video. I think he's had way too little time with the guy to be so blunt, regardless of whether the guy was cool with it or not. I don't think Joe teaches anymore and at least two of his students (Vai and Petrucci) were of near ungodly natural ability. Ear training and knowing the sound of the modes is endlessly beneficial, but not the be-all end-all of playing. There are a lot of modes to train your ears to recognize, although the seven of the major scale form a super solid basis.
On a somewhat related note I saw the Jeff Golub who used to play with Billy Squire and Rod Stewart apparently had his optic nerve collapse in 2011...so all he's got now is his ears. People can read down charts for him, but he's all about applied theory now and listening and reacting. Some players, however, excel at playing arranged music and mainly just need to listen for cues as opposed to improvising and responding in the moment.
All that said Joe's clearly got a ton of knowledge and skill himself. I don't care for his stuff or playing, but I would never deny his ability and the validity f his extremely well informed opinion. I would not, however, appreciate him being so pragmatic with me. I'm well aware of my shortcomings and don't need him slapping me in the face with them. But for some folks, that exactly the kind of teaching they would respond to. It's a somewhat fascinating watch, but I couldn't get through the whole thing, even after multiple attempts.