After trying out many of the plugins available for helping WordPress users embed videos in their posts and Pages, the one that I find to be the best is Viper’s Video Quicktags plugin. Once activated, you can select which types of videos you want to become available on the editor. You can choose from YouTube, Google Video, IFILM, Metacafe, MySpace, Vimeo, Quicktime, generic video file format, and Flash (flv). Once you select the video formats, these appear on your visual editor as icons.
All you have to do is click on an icon, and a pop-up window asks for the URL of the video you wish to embed.