TL;DW: Basically he talks a lot about strength at the end ranges of ROM, and making the ROM greater, also leading to (supposedly) better tendon/ligament strength.
I don't think a baseball pitcher would not know these things, but to an extent, the information is "new" compared to how most in the "strength world" would train ("short range movements" using limited ROM bench press, squat, deadlift, body building movements, etc.). This probably also isn't new for many in TMA, calisthenics, various other "less mainstream" (maybe mainstream for these folks is American football, not sure) athletic pursuits.
Neverthless, found it interesting and thought it might be interesting for some here, especially if you're into eccentric and tendon and fascia. I like what he says about "making shit athletes great". I'm rehabbing my knee using these ideas, basically get a lot of strength and mobility in all the leg muscles and joints. Then supposedly strengthen the tendons and ligaments in the end ranges of the ROM (probably via isometrics and eccentric portion of resistance at those end ranges). And also, lengthen the fascia (short range in the long run would presumably shorten). We'll see how it goes, practically.
https://www.youtube.com/watch?v=uYwBNET_fng