YouTube makes it so SIMPLE!
Showcase your best videos prominently on your sidebar.
Create an account with YouTube where you will host your videos. Next, upload and open the video you want to embed into your sidebar. Right below it, click on the Share icon, then Embed, then Show More.
That will bring up this area below where you will adjust the size/ dimensions of the video frame to fit into the sidebar area.
Go down to Video Size and then pick Custom Size from the drop down menu.
The ideal width for your sidebar is 270, so put that into the first box, and the second box will be filled automatically.
Scroll back upwards and copy the new embed code that’s highlighted in blue below.
In a new tab, go to Dashboard > Appearance > Widgets and drag a Text widget from the lower left side into the sidebar where you want your video to be placed, on the right.
Then click where it says Text as shown below.
Next, paste the embed code from YouTube into the Text widget content area, save and go review your video in your sidebar!
To replace a video, you simply need to replace the code in the text area shown above.