Help with the lesson.......Up One String, Down Another

Ive been Trying The lesson,  UP ONE STRING, DOWN ANOTHER,  and I dont understand how Anders is doing it. when I bend the B string 15th fret up like Anders I push the G string up with it but when i pick the G string and release it I dont get any sound due to my fingers muting the string Im sorry if ive not made any sense but if possible any help would be well appreciated. 

Initially I had the same issue.
(taking a look see at the lesson I'm assuming you mean)

after messing with it a bit...
I think the key is transferring pressure to the G string
(AFTER bending it up with the B string)

after messing with it for a few moments...
I found I could get brief sound from G string
but it instantly dies
then I could get it to last a bit longer; but not full descension in pitch.
and my conclusion is that's just a coordination issue.

this isn't a priority for me right now so that's where I'm leaving it.

but I think I'm on the right track with how it works;
I'm just having trouble executing.

so my conclusion is:
it's just like it says in the lesson description:
"The mechanics of this technique can be pretty challenging at first, but it's an incredibly useful tool and completely worth the hard work!"

(so you just gotta mess with it and alter your approach and observe if that's giving you a slightly better result; or not.

Sorry for the late reply, you are right that’s the exact lesson I’m having problems with and Thank you so much for your help I had left that lesson a while ago but after reading your reply I’ll have another go at it thanks again.

you're welcome

: )

This is definitely one of those tricky little techniques. It can be tough to roll your finger enough that it fully presses down the G string against the fret. If your action is very high that can make it even more difficult. You may or may not want to try lowering your string action at the bridge. 

-Carl.