Two options.
1) If you hold the review button down for about 1 second rather than simply "click"it, it will go into review mode rather than CHDK <ALT> mode
2) You can reassign the button that takes you to CHDK <ALT> mode using the CHDK Settings menu to the Video button. If you click the video button, you get <ALT> mode - if you press and hold it will start recording video.