Grip and release in slomo here
I have also noticed that I can only get this to work when I get closed more than 45º (almost square to homebase). Maybe, that's the reason I could never pitch it faster.
Anyway, as I'm working to get my mechanics improved I'm not throwing anything but FBs.
I'll give it a try next time on the field and hopefully will get more videos to post.
Still working on it ???