I tried to learn from that Sinclair video, too. I found it useful for generally visualizing what the shot will look like, but not for actually learning the shot. He's actually too smooth, if that makes sense.
What happened to me is you know, you're learning a new putt so you aren't confident and you're really concentrating. So one or both things happen: your arm tenses up, or it slows down. This results in a non-spinning, dying quail of a putt. And then you try to compensate with for that by using more wrist, which is also bad.
In Blake's article, he mentions NOT to follow through when you are learning the putt. That, and the lifting off of the fingers are (to me) are the only way to get the feel of the putt. All the power comes from the weight shift. You shouldn't feel like you need to "throw" the disc or generate any effort with your arm or wrist at all, other than simply lifting your arm a bit as you shift weight.
The grip doesn't matter all that much as long as the release is clean. If you have your finger on the side of the disc, it's hard to get a clean release. Other than that, anything that feels comfortable works.
If you get a clean release and a short relaxed flick, then almost any issue with the putt (left/right, too much spin/ nose angle) seems to go away. That's the beauty of it. The motion is so quick and compact that once you get it, you can repeat it over and over. On a non-windy day, you really don't have to actively aim at all.
Anyway, that's my 2 cents. I'm still not as good a putter as I'd like, but mostly because I'm lousy in the wind and sometimes I screw up my weight shift.