Let's say you upload a video to a site like YouTube and you want to see who viewed your video and where. An important number of views come from other sites that embed your video or link to it. You can use Google Blog Search to find them.
Find links to the video
A YouTube video has an address like: http://www.youtube.com/watch?v=o-KWYYIY4jQ. Paste the address in Google Blog Search and you'll find blogs and forums that link to the video.
Find sites that embed the video
You'll need to look at the code that needs to be added to a site and note the address included there: embed src="ADDRESS". For YouTube, this is a small alteration of the previous address and is similar to: http://www.youtube.com/v/o-KWYYIY4jQ. Now that you have the address of the embeddable Flash object, paste it in Google Blog Search and find a list of blogs.
An easier to find both kinds of blogs is to go to Technorati and to type the address of the video, but this only works for YouTube, while Google's Blog Search works for other sites too.