Due to an issue with YouTube, inserting videos in your emails is showing an error. Until they are able to resolve this issue, we recommend using a different video hosting service. We will continue to monitor this outage and update you as we have more information.
I am looking to do the same, from what I have read, the API does not support SSL - it may be something we have to get CC to work on for us.
If you are talking about the width of a block, then look at "Advanced Features", then "Edit Style Sheet". Usually at the bottom are the settings for template width, right column width, and left column width. You can edit these, but save your email first and edit with caution. Make sure your right and left column widths add up to total template width. You could also do some tweaking in the html code view for each section you are editing in the email. But only do this if you understand html code.