@xgreenjacket, Look at the lesson again. Justin uses his middle and/or index finger to move the upper string out of the way.
thanks but i'm not sure thats a conscious thing he does...
I believe it is.
It is the way to stop the next string sounding - you need to use the 1st and/or 2nd finger to gently push the next string out of the way, and then to release it gently when you release the bend to avoid the pull-off sound (muting with your palm also helps).
It's just something that falls into place with careful practice.
I find that there is a sweet-spot for the action: Too high, and your fingers slip under the next sting; too low, and you can't get a good 'grip' on the string you're bending - it seems to slip under the finger you're trying to bend it with.