First, understand that You Tube allows posters of videos to allow anyone to take those videos and embed them on their own websites. That's part of the user agreement.
You (poster/account holder) hereby grant each user of the YouTube Website a non-exclusive license to access your User Submissions through the Website, and to use, reproduce, distribute, display and perform such User Submissions as permitted through the functionality of the Website and under these Terms of Service. The functionality in the last line is the "embed" code adjacent to each video. If the code is there, another website may use that code (the functionality) to embed the video on their web site.
Ok so far.
Now, Associated Press has gotten miffed at a radio station in Tennessee for embedding codes of Associated Press videos on You Tube on the station's web site.
Here's how PC World covered the story.
And for added emphasis, here's an embedded Associated Press video for you to understand what the content is, where it came from and the functionality (embedded code) of the You Tube posting by AP.
Click twice on the video image to go to the Associated Press pages on You Tube. To the right of the video, you'll see the "embed" code. If it's not there, then they've taken it down. If they've taken it down, you didn't see the video above.
Easy as that to understand.
By contrast, the Reuters You Tube site does not offer an embed code. So there is no way to post their videos directly on another website.