When you double-click a movie in the Project panel, it opens by default in the Footage panel or in a player window: QuickTime (.mov) files open in a QuickTime Player window; Video for Windows (.avi) files open in a Video for Windows player window. Still images always appear in the Footage panel. Certain AVI files are not supported by the AVI player window, and will open in the After Effects Footage panel. These include files created with Microsoft’s DirectX DV codec and all files over 2 GB.

To open a QuickTime or Video for Windows movie in the Footage panel instead of a player window, Alt-double-click (Windows) or Option-double-click (Mac OS) the footage item in the Project panel.

The QuickTime and Video for Windows player windows play the source file, not the edited and interpreted footage item based on the source file.

You can use the Set In Point , Set Out Point , Ripple Insert Edit , and Overlay Edit controls in the Footage panel to trim a footage item and insert it into a composition. This can be more convenient than adding the footage item to a composition and then trimming in the Timeline panel.