Video is tough to do correctly
When video is done correctly, it's a wonderful addition to a web site. You can communicate many different ideas in video format effectively and quickly. If a picture tells a thousand words, a moving picture with sound tells thousands of words a second.
On the other hand, poorly done video can turn an excellent site into a nightmare for the user. A webmaster cam, with poor use of video, make a site virtually unusable.
The first thing to remember about video is speed. Video is, by it's very nature, slow. Depending upon the format used, it can be very slow indeed, even for users on broadband (cable or DSL). For users on dialup lines, it can be absolute murder.