Start chatting.

Brain Pick is easy-to-use and it only takes a few minutes to sign-up using your LinkedIn account. Then simply search for the topic you want to pick someone's brain about to see who's available and request a chat with them. 

You can message each other to co-ordinate schedules, and once you agree on a day/time, the video chat works exactly like FaceTime.  Everything is 100% private and secure, and you can chat for as long as you both like.