Most video sources these days are happy for you to embed their clips into your blog. Here are some (usual disclaimers included). A simple tutorial follows the list below. You might also want to use TubePrompter with these links.
All you have to do is copy the “embed” code at any of these links below (+ many others). The embed code is often seen in a text area near the “share” options and noted with icons like this:
All you have to do is copy the embed code – don’t even look at it – it’s too scary.