When you are SMIL multimedia presentation with other people involved, you should always go through everything together. In front of an audience, you don't want to seem unprofessional and sloppy when you don't know who is supposed to do what.

Sit down together and hash out the details. There are many elements that must be discussed. If you have any presentation aids, you should create them together. Determine when each person is going to speak and when they will speak. When one person leaves off, the other should pick up. Don't leave anything out. Even decide where each person will stand to prevent any confusion.