I agree with others. It's kind of silly to expect dog to be calm and okey watching others run 
I'm the lucky person who have both - dog who can sit and watch agility and at the same time the dog which is extremely enjoying running the course and puts the excitement into the run. Though, I witnessed how other people who are attending the class with us have been struggling with their BOC. I've never seen such a crazy behavior in my life. She always nearly choked on her leash as she was jumping around or trying to run ahead, but the leash would always stop her. The owner had to leave outside and it was too bad. Their dog didn't control itelf at all. They discussed it with few people/dog agility trainers and they've been told that they have to make her busy, exercise with her on the side, try to do some tricks etc. ALSO what me and others suggested was to get her used to the crate. I think it's necessary for this kind of a dog... and well, in general for everyone to be taught how to relax in a crate. In general, I think the exercise thing helps a lot, but both -dog and a handler should be able to get some rest. 
When they first tried play with a ball with that BOC and give her some commands, even when she was off leash, she was so cool. It was a miracle. So from my own experience either play with a dog or put him into a crate and cover! the crate.
I'm the lucky person who have both - dog who can sit and watch agility and at the same time the dog which is extremely enjoying running the course and puts the excitement into the run. Though, I witnessed how other people who are attending the class with us have been struggling with their BOC. I've never seen such a crazy behavior in my life. She always nearly choked on her leash as she was jumping around or trying to run ahead, but the leash would always stop her. The owner had to leave outside and it was too bad. Their dog didn't control itelf at all. They discussed it with few people/dog agility trainers and they've been told that they have to make her busy, exercise with her on the side, try to do some tricks etc. ALSO what me and others suggested was to get her used to the crate. I think it's necessary for this kind of a dog... and well, in general for everyone to be taught how to relax in a crate. In general, I think the exercise thing helps a lot, but both -dog and a handler should be able to get some rest. When they first tried play with a ball with that BOC and give her some commands, even when she was off leash, she was so cool. It was a miracle. So from my own experience either play with a dog or put him into a crate and cover! the crate.