Pedro, unfortunately, doesn't know what he's talking about in that video.
The research is pretty clear - if the trunk rotates before the lead foot strikes the ground, then it does add stress to the elbow. But watch Koehler's Miami logo on his jersey...it barely moves, meaning his trunk does NOT rotate before his stride foot lands). You'll see that Miami logo rotate forward with his body AFTER his foot lands.
Unfortunately, a lot of great players don't necessarily know how to teach, and the biomechanics of pitching are kind of complex. You're also right that in Pedro's own delivery, his foot lands at 45 or so, but though it is ideal for the foot to land a bit closed (up to 45) it can't land too much more than that or the hips won't open fully - the planted cleats and the limits of ankle, hip and knee flexibility won't allow it. I teach a 1 o clock landing, which is as closed as the foot can be while still allowing the hips to open.
Never heard of anyone pointing the back foot at 45 like Candrea recommends.