I've had similar problems, never really good in the takeoff or landing department. I was playing around with my Hobbyzone Champ the other day to practice just that. I did some experimenting doing about twenty minutes of just taxiing around the driveways playing with rudder and throttle.
What I noticed was this: As the tail starts getting light, but not quite ready to lift, the plane has a greater chance of doing a ground loop. At low speeds with the tail firmly planted it will behave. Once the tail comes off it behaves and as it's such a light plane usually just takes off at that point. It's really only the brief period when the tail is starting to lift but hasn't come off the ground when the trouble happens.
So, possible solutions: 1)Hold slight up elevator to keep the tail down and keep control. 2)Firewall the throttle right off so your have more air over the rudder, giving it more control and lifting the tail quickly, reducing the time it's in that twitchy in-between stage.
This is just what I've observed on my little champ. Your mileage may vary.
One thing I noticed in your video was your plane's tendency to bank right on takeoff. That may be a trim issue that's throwing things off.
I was reading another article on improving landings recently that had this to say: Throttle controls decent rate, angle of attack controls speed. If your plane is sinking quickly, but coming in at a good speed, bump the throttle a bit to reduce the decent. If you're coming in fast, don't chop the throttle to slow down, you'll just drop out of the sky. Give a little up elevator and you'll slow it down.
The most important thing when flying a taildragger, fly it all the way to the ground. Keep airspeed up so you don't stall out of the sky. Get the wheels on, then pull back the throttle to settle the tail in.
If you manage all this please teach me how. I'm still teaching myself and the weather here in Syracuse is not being cooperative lately.
