CLEAN: A message from Obama welcomes the IOC to Chicago

The video introduces the community and volunteers, welcomes viewers to the United Center in Chicago, and highlights the importance of gymnastic facilities. It emphasizes Chicago's significance as a quintessential American city and its suitability as the host city for the 2016 Olympic and Paralympic Games.

What role do volunteers play according to the text?

What does the speaker express confidence about regarding the host city?