Video is complicated by the fact that it it is regulated by copyright law. The person administering your wedding will explain this - but it does incur a fee because a licence must be obtained to legally video a wedding.
We are happy for photography during the service but we ask thn congregation not to use flash - because it can be off putting for you if you're saying vows and get the light in your eyes. We do ask photographers to move about as little as possible and be completely unobtrusive.
Professional photographers usually know how to do their job and we're happy to let them get on with it!