In some brainstorming sessions, the ultimate goal is to get the participants to expand their imagination and go for big scary audacious ideas that have impact and can change the world. This is easier said than done if the group is a high performing execution machine used to a linear process where they optimize the time to a working solution. This type of group sometimes needs a little encouragement to stay in the problem space and come up with big ambitious ideas.
If the group participating in the brainstorming session don't have a lot of experience with blue-sky, outside-the-box thinking, and have a tendency to come up with well-understood, incremental solutions, there is a video that can help them get out of their comfort zone and think big. It is James Currier's "Hit it Hard". It's short, funny and very insightful and can help the group take a little bit more risk during the ideation session.