Here is an example of how ads are placed pre and post-roll to an on-line video. In this case it is BWM (You can fast scroll to see the post-roll placement). This to become the prevalent model on-line. Text links are here to stay but the return is always higher to a medium that engages all our cognitive modalities i.e. the more engaging videos. As bandwidth and access resolve themselves (and easy to use players go to market), on-line videos will be the prevalent ad model whether stand-alone or wrap-around. The democratization of filmmaking is here-the videos and the ads.  Webcams and digital vidcams are flying off the shelf.