I recently saw this video and was very touched. As I've stated before, I served a mission. I too received a "call" as these people did. I didn't choose to go to Chicago (where I was called), but I definitely felt it was an inspired decision by my Church leaders to send me there. Young people- "Elders and Sisters" as we call them, serve for 18 to 24 months. They share the message of our Church full-time every day. It is completely voluntary, unpaid service (however, I feel that I have been "paid" in so many blessings).