Embedded Video
You can embed a video into your web page simply by copying the <iframe> embed code, which should be available from your video source, and pasting it into your content block (while in the "Source code" view of the page editor).
You can also "dress up" the iframe itself. I like to center the video, remove the hard border, round the corners, and add a drop shadow, like the example above. This can be done by styling the iframe with style="border: 0px; border-radius: 4px; box-shadow: rgba(60, 64, 67, 0.3) 0px 1px 2px 0px, rgba(60, 64, 67, 0.15) 0px 2px 6px 2px;" like this (the code goes within the <iframe> tag immediately after "<iframe"):
<p style="text-align: center;"><iframe style="border: 0px; border-radius: 4px; box-shadow: rgba(60, 64, 67, 0.3) 0px 1px 2px 0px, rgba(60, 64, 67, 0.15) 0px 2px 6px 2px;" src="https://www.youtube.com/embed/XndqfBTv6Bg" width="560" height="314" allowfullscreen="allowfullscreen"></iframe></p>