Thanks for all the answers they have been very helpful.
Can someone exaplain to me, or give a few examples of the idea talked about above about using B roll as punctuation to the points, im a little confused by this.
Is DVD the only format where you can insert the anamorphic flag which tells your hardware to swich between 4:3 and 16:9, im assuming you cannot do this with formats such as digi beta etc.