During this week I would like to talk a little about video using the DSLR. Any DSLR may in the last 3-5 years have had a video function. This is convenient in many ways, not the least of which is that you do not have to carry two cameras along with you. DSLR's also have the advantage of over dedicated camcorders in that one can control the depth of field. Consumer grade camcorders often try to put EVERYTHING in focus, which can be a little distracting to the viewer.
Another definite advantage is that one can merge still images with the video to produce an outstanding product called fusion. Youtube is very popular and many videos merge both stills a video to produce some impressive presentations. Of course, those who photograph weddings as well other events realize the importance of video along with still photography.
Video of course is about storytelling instead of freezing a single moment in time. It does require a little more pre-production time. This may mean understanding the flow of the wedding, and event, or discussing in depth your ideas with your talent before you begin the shoot. Some photographers will develop a 'mood board' even for still photography. This is a series of concept images, that me even be hand drawn, that lets everyone focus on the primary concept, know where the start, middle, and end result of the project may be to develop a quality product.
To start out in video, you really don't need a lot of extra equipment, although there is plenty of video equipment out there. Apart from your camera you will almost definitely need some sort of fluid head tripod or shoulder rig. Hand holding a camera during video can result in a very unstable image, particularly if you the subject is moving. Amazon.com sells a variety of FLUID head tripods and shoulder rigs for video photography at prices ranging from $80 to $250 depending upon the manufacturer.
I have included a link based on a Mark Wallace presentation as a starting point for video.