A website called wonderhowto.com is now hosting over 10,000 'how to' videos on everything from educating, building, and instruct on different 'how to' projects.
As the website itself relates : "We start by asking a simple question. Does the video possess the intent to instruct the viewer? Some videos have the intent to promote, entertain, or inform: but that is not the same thing as the intent to instruct. Is the process of the how-to clearly delineated with requisite ingredients, tools, and details? After viewing the video, can you do-it-yourself? If the answer is yes to the above, we want that video."
If you go to their site, you'll get instructions on how to make the trebuchet shown in the picture here.
"Very neat! A lot of informative videos, some stuff I definitely want to try!"