It's hard to resist the YouTube hotness -- especially if you feel like blogging about the adorable kittens you just saw on YouTube because all your friends must absolutely see it. Sarcasm aside, there are plenty of reasons to embed videos on a blog or web site, but there's something to consider: the embedded video might be used to track your visitors!
Frankly, any content embedded on your site but hosted by another site can cause privacy concerns. When the content is requested, the user's cookies go along with it. The effect is that not only does YouTube know what site a user is on when viewing the kitten video, but they potentially also know who the viewer is! This means that unless you log out of YouTube regularly, they know all the videos you've viewed and on what sites you saw them.
This isn't breaking news. This stuff has been around for a while, it's just Not Obvious.
So you run a blog or web site and you don't want to aid in YouTube tracking your visitors. What do you do? You have three options in my view:
1. Use YouTube's privacy mode. You can embed videos that suppress sending cookies until the visitor has clicked to watch them. This works by changing URLs for any content automatically loaded by your site from the domain "youtube.com" to "youtube-nocookie.com". This way the cookies (for youtube.com) aren't sent until more content is loaded from youtube.com after the click.
2. Don't trust 'em? Use EFF's MyTube. This does something similar, but the static content is loaded from your own site, then when the visitor clicks on the video, it is loaded from youtube.com and the cookies are sent.
3. Open Video FTW! If possible, host the video yourself (on your own website) and use the <video> tag! More info here. Flash is not the only way to display video on the web! Use open standards!