In the case of a You Tube video, observe below the video, in the lower left, are 3 choices:
(1) add to (2) share (3) ... more.
Selecting "share" will give you 3 additional choices:
(1) share (2) embed (3) email
Selecting "embed" will cause the "embed code" to appear in the nearby field. It looks like this:
.<iframe width="420" height="315" src="//www.youtube.com/embed/7lUFPYevUFY" frameborder="0"allowfullscreen>.
Copy that code and paste it between the HTML tags in your post.
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