There are many, many ways of doing this, but Download YouTube Videos as MP4 is one of the simplest and most reliable plugins I’ve ever used. I use it for embedding video clips in PowerPoint when I’m lecturing, because if you’ve got a YouTube clip that you really want to show someone else
- there’s a risk that it might have been taken off-line by the time you go to show it again
- if the internet connection fails or is slow, you can’t show it at all
- clips load much quicker when they’re already on your local computer rather than being streamed off the web
Once you’ve installed the script, it adds a little menu item on every YouTube page right under the video that gives you the option to download it as MP4 or FLV.
Just a word of warning though – don’t press any of the green ‘download’ buttons: to install the script, just go to the top right hand side of the page and press ‘Install’ (see below) – all the ‘download now’ buttons refer to other things sitting as ads on the page, and are nothing to to with the script.
If you use it in Firefox you need to install Greasemonkey first, but it works straightaway as a plug-in in Chrome. See directions on the page for other browsers.
By the way, I know that downloading YouTube clips and storing them is probably illegal and violates all kinds of copyright laws, but I take the view that when I do it, I’m using the clip temporarily in an educational context, and I wouldn’t upload the video again to another site, or distribute it on a CD or DVD.