I believe my initial problem was to play doubles as Dave demonstrated to literally. I was trying to do it as demonstarted (slowly) but only faster. Your hands are actually ON the stick constantly, there IS no opening and closing of the hand super fast and that was my block.
Ah, well, then allow me to suggest the most important thing to keep an eye on is your fulcrum as you work on this slowly. Make sure you're getting stick pivot. If your wrist is doing all the pivoting and the stick is not pivoting between your fingers, you'll pay for that sooner or later. It takes longer to build up speed when you're also working to maintain a decent fulcrum, but you'll eventually figure out how to work the back fingers to regain control of the stick on the rebound ... and that second stroke in the double stroke will become more of a function of stick intertia and finger snap than actual wrist stroke.
Do that in earnest over a couple of months and your doubles will be cleaner than a baby's butt at any tempo and in any expression.
Something else to consider is practicing doubles over a triplet skeleton. This is how I usually get my students going. They play a bar of triplets and a bar of doubles over the triplet. The doubles are sextuplets -- not 32nd notes like you would get with a double stroke roll over sixteenths -- but they're easier to clean up. It's just a more "open" skeleton pattern and easier to pull off at first. I think it's human instinct to relax during triplets, anyway. Don't know.
If that's too much, just use an 8th-note skeleton and play 16th-note double strokes for now. You should be able to hear them and get them lined up so they're metrically accurate.
