It does not look like an issue with binding.
Some recievers need to be turned on after their radios. This was an old saftey precaution that some new flightcontrollers and radios adopted. This is a common problem with the KK board. I do not think this is the problem, but listed it for others who are with a similar problem.
The quadcopter usually won't idle on arm unless you set it to. I personally don't use it because of the newer flight mode called airmode which makes it obselete.
If I had to guess what the actual problem is it would be that the reciever is in PWM mode and it is connected for PPM or S-BUS, assuming the Rx is capable of PPM.
This video should help if that is the case:
Also I'd take a look at this before flying:
I know this is for cleanflight, however much of it will be relevent for betaflight
http://www.propwashed.com/flight-controller-software-set-up-checklist/
--Edit--
Just rewatched your video and yes, PPM output should be on, and the betaflight reciever settings should be set for PPM or CPPM as well.
