A skin is like a frame around your QuickTime movie. You can make your movie look like it?s playing in a TV, or a car windshield, or whatever else you can imagine. Your movie doesn?t even have to be rectangular. Here's how to create one (note that this hint requires QuickTime Pro).
First create an image file using Photoshop or some other graphics program. You can use a photograph or clip art or draw something yourself. Within this file, fill the area where your video will play back in black or white. Save the file as skin.png. Select all the area where your video will not play and fill it with black. (In Photoshop, if you have the video area selected, you can press Shift-Command-I to invert the selection and select everything other than the video area, then fill it black.) Fill the other portion of the image with white. Save this file as mask.png. Finally, fill the entire skin with black and save that as black.png. All files should be saved in the same folder.
Open your video with QuickTime Pro. Then drag skin.png to the QuickTime icon in the Dock, and it will open in a new QuickTime window. In this window, hit Command-A to select the entire window's contents. Hit Command-C to copy it. Hit Command-W to close this file. Select the QuickTime window your source video is in. Press Command-A to select All, then pick Edit -> Add to Selection and Scale.
Hit Command-J to open the properties. Select the video track for your skin. It will say PNG in the format column. At the bottom left of the Visual Settings tab, click Choose to select a mask, and select the mask.png file you saved earlier. At the top of the Properties window, click on the track for your video, and use the offset fields to line up your video in the hole in your skin. If your video does not show through the skin, click the Invert button. (Your skin should already be in a layer on top of the video. If not, use the Layer field to adjust as necessary.)
Go to File, Save As, and save the file as vid_skin_mask_combined.mov. At this point, you should see your skin as you?d like it to appear, except it?s inside a regular QuickTime viewer. The last step gets rid of the viewer. Create a plain text file and enter the following:
<?xml version="1.0"?>
<?quicktime type="application/x-qtskin"?>
<skin>
<movie src="vid_skin_mask_combined.mov"/>
<contentregion src="black.png"/>
<dragregion src="black.png"/>
</skin>
Save this file as text.mov -- the .mov is the important part. Double-click text.mov in Finder. You should see your skin and video without a QuickTime window. To make this a standalone movie, click File -> Save as, and save it as a Standalone movie. If you don?t want to create your own skin and mask files, you can practice with the files provided here. You can also watch the steps performed in a screencast.
Mac OS X Hints
http://hints.macworld.com/article.php?story=2007012607342163