Now sure there are many pitfalls with using a stills camera to create a wedding film. Even the advantages of the portability and size can become its own disadvantages in terms of keeping it steady and using it transitionally while keeping focus. Many of the video solutions for the DSLR cameras actually take away from the advantages of the camera.
Wedding cinematography is the art of creating a film-like movie of a live wedding day. This is not an easy thing to achieve and to pull off! Filming a live event using cinematic techniques is very hard! Not only do you not have the same level of control of sound and lighting as you would in a movie, you also have next to none preparation time in setting up for each shot.
Using portable equipment like the DSLR cameras and small 1 metre tracking rails add to the quickness you are able to capture a shot and also the fact that these cameras cope pretty well in low light and changing a battery lens or card is a matter of seconds not minutes.
Still filming a wedding video with a stills camera is tricky.