I am getting a video because my sister & several friends who opted not to do it regretted it. Both they and friends who did get a video all say the day went so fast that a video is great for helping them relive the day and seeing lots of little things they totally missed or were unaware of.
A few say they also watch it when they get in a big fight with their hubby - it helps take them back to that day & remember why they said "yes" etc..so I figure having it on hand for this purpose also can't hurt
As for your guests who film the day, you may be surprised. I think someone will definitely post it online - especially if they are also film & broadcasting friends. I work in broadcasting & my colleagues are really into photography & film making and always share their pics and flicks from everything we attend (showers, birthday dinners/office parties, weddings and even work trips).
~ i've learned that people will forget what you said, people will forget what you did, but people will never forget how you made them feel. - Maya Angelou ~