I watched for awhile (I LOVE watching calves being born) but my kids got hungry and wanted to leave. My mom said, "Don't you think you should call Kris? There's only one hoof out."
Later he refreshed me on 'reasons a cow needs help calving.' One hoof - bad. One hoof and head - bad. Back feet - bad. Two front hooves - good. He and the employees chased the one-hoof-coming-out-cow into a barn freestall, where he could help her without chasing her all over the pasture. (Cows having calves tend to run away. As you can imagine, this doesn't help the birth progress.)
Then he had to push the calf's hoof back inside her and maneuver it until both of the hooves were coming out with the head following. Then he was able to pull the calf out. Both cow and calf were fine.
He also showed the boys and me a little two-inch scratch on his arm. No, calves can't bite, but when you're pushing and pulling - the calf's teeth had scraped some of his skin off. Welcome to the world, little calf! I guess my kids weren't the only ones who were hungry.