...I recently had a simple idea on how to improve the handling of racing multirotors, and just implemented this feature in my flight controller.
Background here:
http://shrediquette.blogspot.de/2016/01/some-thoughts-on-camera-tilt.html
Almost every 'serious' FPV racer is tilting the FPV camera up in order to have a better image during fast flight. Angles between 10 and 35 degrees seem to be common. E.g. I am using 25 degrees. But tilting the camera with respect to the multirotors horizontal plane has a side effect on the controls (maybe you never thought about it, because you are so used to flying with this side effect).
'FPV camera tilt compensation' eliminates this effect, and I think it enhances the flight performance of your racing multirotor.
In Betaflight, this parameter is called Fpv_mix_degrees or roll_yaw_cam_mix_degrees
Please note that this was my first flight with a large camera (GoPro) attached to a racing copter. I was a bit surprised by the negative impact of the extra weight & drag, and I was not really feeling confident yet. I do not really understand why people deliberately choose to fly competitions with action cameras mounted on their machines... X-D