piStabilize is a video stabilizer plug-in for iMovie and eliminates unwanted shaky motion from video clips. The stabilization accounts for translations, rotations, and zooming. Margins, a common problem of video stabilization, are filled with appropriate colors to make them less obvious, and they can optionally be reduced by zooming. A smart zooming technique applies zooming dynamically and ensures a minimum of image degradation due to magnification. piStabilize utilizes a caching technique for computed motion, which saves from repeatedly computing motion when reapplying stabilization. This significantly improves performance and efficiency in practical use.