Preview Video, Image, and Audio Clips

Once a file has been added to the "project files", there is currently no way to preview the file. The user has to add the file to their timeline, and click "Play". There needs to be 2 easy ways to watch/listen/preview a clip:

1) Double click any file in the "Project Files"
2) Right click on a file, and choose "Preview File"

The preview should show up in the main video window, and all of the regular video control buttons should work (play, pause, seek, etc...). Once the user clicks back on the timeline play-head or timeline ruler, the preview should stop, and return to the timeline output.