If the source file for a video layer is modified in a different application, Photoshop Extended generally reloads and updates the footage, when you open the document containing the video layer referencing the changed source file. If your document is already open and the source file has been modified, use the Reload Frame command to reload and update the current frame in the Animation palette. Navigating through the video layer using the Previous/Next Frame or Play button in the Animation palette should also reload and update the footage.