(Keep in mind here that I am no html expert lol. this is how I do it and what I use.) Check the Description for the embed code as well.
so I get asked this a lot and it really is quite simple.
First things first, you will need the ID tag at the end of the youtube URL. and you can it from 2 places: either directly from the URL or from the share tab below the video itself. If you get it from the page URL is the bit after the = sign. From the share tab its the bit after the / symbol.
Copy that ID. now you will insert it into the html code used to embed the video in a Deviant Art journal
so to make an example, if I use the ID from the Picture Perfect Pony video made by JanAnimation, sDdL4z5qfr4
I put it in the code below (Keep in mind there are spaces between the <> symbols and the spaces can't be there for the code to work.)
< da:embed profile="youtube" id=PASTE ID HERE >
Here's the code with the ID, again with the spaces in the <>.