I watched the video again and thats true, only the takeoffs were instables. I also noticed that there was a XBee in your quad. Are you using XBee to control the quad either? What controller are you using?
I'm doing a project that is almost the same as yours, diverging that I'm gonna use XBee as the transmitter. Now I'm really scared, cause everyone I see using this frame ends in tragedy in the first flight.
Look, was the stabilization system working well? Just accelerating up is not enough to a smooth take off?
I've made a wireless controller driven by movement, with support so plugin pedals and a software to emulate a normal Joystick in order to make it usable in any Windows software, game or simulator. The chip was programmed by an Arduino board.
It's pretty cool. See the video below:
For any question or detail you can ask either in here or in the video comments.