Hey Guys. We are shooting a MV, there is scene we need to show the actors in city center driving a car and having conversation in the car, in the mean while there something happening outside the car at the footpath. There is no way we can have a towcar at the central city, nor we can mount a camera on the car and take many takes. So we were thinking to do a Greenscreen. I need some advise here, anything that I need to pay extra attention to and any suggestion would do great help!!

Thanks

Here is a tutorial over at Digital Juice

http://www.digitaljuice.com/djtv/segment_detail.asp?sid=194&sortby=&page=3&kwid=0&show=all_videos

You also might want to try Youtube. There are a number of how-to videos there.