Cheerleading Witnesses?

Hebrews 12:1 states (in the KJV): " Wherefore seeing we also are compassed about with so great a cloud of witnesses, let us lay aside every weight, and the sin which doth so easily beset us, and let us run with patience the race that is set before us..."

At church this morning, the pastor was interpreting this to mean that the great witnesses to the faith of Hebrews 11 were cheering Christians on, as Christians ran the race.  I've heard this sort of interpretation before.  Surprisingly, I heard it at an independent Seventh-Day Adventist church, and the pastor there was actually imitating a cheerleader, his point being that the great witnesses are like cheerleaders.  The reason that this was surprising to me is that Seventh-Day Adventists believe in soul sleep: they don't think that the souls of the dead are conscious and in heaven between death and the resurrection at the last day, but rather that the dead are in a state of unconsciousness.  In that scenario, how could the departed great witnesses to the faith cheer on Christians today, when they are not even conscious?

Before I heard the interpretation that the witnesses according to Hebrews 12 are in heaven cheering Christians on, I suppose that I interpreted Hebrews 12:1 to mean that we can be encouraged by the past witnesses' example.  I was in a church that believed in soul sleep.  But I have reservations about my previous view.  Why does the text say that we are surrounded by this cloud of witnesses?  And what is the relevance of the cloud?  I can envision the witnesses surrounding us, as in an arena, cheering us on.