Trim Your Video
At the top of the Animation panel (in Timeline mode), you will notice two blue handles at the ends of the Work Area bar. This is your work area. You can drag the Work Area Start and Work Area End handles to specify how much of the video you want to work with.
That is a no brainer but this is useless. I want to clip the video to delete video in the timeline before and after the area I am working with. Can this be done in Photoshop CS4?