Adding youtube videos related to your sites niche and then reflecting upon it in your post is a very easy way to get interesting quality content for you site. You can even add relevant affiliate links in the post. Double Click on the video while playing to view it in full screen. Double Click on the full screen video to return to web view mode.

You add a YouTube Video by using the src link from the embed code for the video. I have pasted in the embed code for this video below so you can easily see what I mean with the src link. I.e. the code below does not show up in your post when you use a YouTube Video

<object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/yRVi0paZlfI&hl=en&fs=1"></param>
<param name="allowFullScreen" value="true"></param>

<embed src="http://www.youtube.com/v/yRVi0paZlfI&hl=en&fs=1" type="application/x-shockwave-flash" allowfullscreen="true" width="425" height="344"></embed></object>

You get the preview image by right clicking and saving it to your HD for that video from youtubes preview image.