i use a program that used to be called snatchit, but is now called frameshots. it's sooo easy, fast, and very little learning curve. you can do whatever you like - every 5 seconds is no prob. use the highest quality, and as long as the videos aren't blurry, you can use it for webmaster content.

http://www.download.com/FrameShots-V...ml?tag=lst-0-1 here it is, and it's a whopping $30.