I watched the video again. It shows that after Mo falls, Galen goes to an outer lane and drops back significantly. He then talks to Mo. See 1:10 in this video:
http://www.nbcolympics.com/news/mo-farah-wins-back-back-10000m-gold-medals
What does he say to Mo?
"I told him to get behind me after that and I’d help lead him back up,â€
Class act.