Pixhawk arducopter instable flight

I have a s500 quadcopter with a pixhawk flight controller.

I initially build the drone and calibrated all hardware components according to the ardupilot documentation. After this the copter flew great and performed well in stabilise, RTL and guided modes.

After this I continued with my project of automatically guiding the drone in guided mode according to a person in a camera feed. During this development time the drone had some crashes. After a while I started noticing the drone was not flying stable anymore. First I thought it was my own drone kit code guiding the copter not correctly.

To test this I flew the copter in stabilise mode. And in this mode I saw the drone twitching a lot. Please see the flight footage from this link:

Also I notice I have to give a lot of throttle to get the drone to go up if the drone is in a descending motion.

After the flight I also notices 2 motors where getting really hot while the other two where not.

Are two of my motors broken or is something else wrong causing the drone to not fly stable in stabilize mode?

Thanks

Sieuwe

Best to post a .bin log file and we can tell a lot more.
Hot motors could be physical or electrical issues with those motors or ESC, or they could even be driven harder (and heating up) if the props are slipping. Normally slipping props would result in a crash though.

Hi I will do that today. Also I just noticed that the video was not working. I uploaded it again and updated the link.