Hi Richard-
This is a great question. There are a couple of ways to modify the size of your embed without the text editor. You can use one of our pre-formatted Video Blocks which will give you several options for layouts with your video.
You can also use the drag-and-drop borders of the Video’s container to modify the size. That being said, you can get the most control over your size with the Text Editor. I put together this video to demonstrate the different ways.