Yes, of course you can - and it is every easy to do so.
Hit "edit" at the top of your hub, and when in edit mode look to the top right for the capsules, and click "video," and that will load on the bottom of your hub just above the comment capsule.
You can use the arrows to move the vid capsule anywhere you wish. Click "edit" on the video capsule, and paste in from a separate tab or window the url of the youtube vid you wish to have in your hub. Click "save" on the vid capsule, and then click "done editing" or "publish at the top of your hub - you are done, unless you wish to add more, or continue editing.