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A window will then open allowing you to Paste the URL as well as a description of the video being linked. 
When you have provided all the needed information, click "Insert". This will embed the video into your content. (Note: If the video in question has settings that prevent embedding, these features will only provide a link instead.)
Linking Videos Directly
Sometimes you may not be able to use the Mashup search to add the video. You may be sharing one of your own unlisted videos, a video published with settings that prevent embedding, or you may just find it more convenient since you've already located the video that you want. If this is the case, you can directly link the video.
First, find the video on YouTube, and copy the URL at the top of the browser.
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Select Link from the list of options, and paste the copied URL into the space provided.
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Click Submit, and the link will be added to Scholar. Note that this method does not embed the video to be viewed from within Scholar, but links out to the YouTube video's primary location.