Embedding a video hosted on another server is a very easy and quick way to provide content on your website. All you need is the "embed code," which can be found somewhere on the page where your video resides. You sometimes have the option of customizing your embed code, according to the size and borders. On this page I've embedded a Screencast video I have published to my account. All you need to do it click the Code view on your Dreamweaver document and paste the embed code on your page.
You can always adjust the size of your video by dragging the corner handles on the video placeholder (hold the Shift key while you are doing this).