First run the video by clicking on the link provided at the beginning of this thread. After the video has completely played leave it up. Go to Windows Explorer and find your Temporary Internet Files directory (usually found in the Windows directory). Look for a large temporary file with 23,354 KB and a file name containing "howstuffworks" and copy it to another location on your hard drive.
You can now rename it, but leave the .flv extension alone. A file with a .flv extension indicates it is a Flash Video.
To get a good explanation of what a Flash Video is and how to play it go to:
AfterDawn.com: Guides: How to play FLV files
Hope this helps - I know, clear as mud right?