Sturgeon's Law might appear too generous when applied to the web wonder, YouTube. Still, the online video resource does have its moments. Among them, physics and critical-thinking "teachable moments."
Having grown up in the Mac OS, I've become accustomed to easily acquiring anything in my browser window with a click (or at worst a modified click) of the mouse. But the videos on YouTube (and some other sources) exist in Flash Video format. You can't just click a QuickTime pop-up menu and download the clip to your hard drive.
If the video clips stayed at YouTube forever and I had universal, uninterrupted access to the Internet, there would be no problem. But, you know; reality...
So here's what you need to do, fellow OS X users hoping to acquire elusive video content. I admit I'm a complete neophyte at this, so easier/better ways may exist. Enlighten me in the comments.
1. Watch the YouTube (or other enlightening Flash Video) clip on Safari.
2. From Safari's Window menu, select Activity.
3. In the tangle of addresses, find the one URL that's big (MB's instead of KB's) and ends in ".flv."
4. Double-click it right there in the Activity window. This will download the file into your designated download destination.
5. Get iSquint. Open iSquint, and use it to transform the .flv file into a .mp4. You have some options; I don't recommend H.264 unless you've got lots of time to kill and hard drive space to spare.
6. If you want to completely transform the file to QuickTime format, you'll need QuickTime Pro. Open the .mp4 in QuickTime Pro and Save As a ".mov" file. And give it a more descriptive name than what it downloaded with!
Again, this post is for Mac folks only; PC-types can tell me how much easier their process is in the comments. If there is an easier way for OS X, don't keep me in the dark.