There is an application for the iPhone called Silent Film Director that is so much fun. You can create your own silent film! And, I believe that the application plus the upgrade you are going to need will run you around $3... not too bad. You have to be a little bit technical or know someone who is, but it can turn out just so cute. You could use it as the wedding video or the invitation, using 1920's music downloaded from itunes. You can make placards with cardboard to include exclamations like "He proposed... GASP!" But, if you look at the demo video, you wouldn't have to do that if you didn't want to because the video can include messages in a variety of appropriate fonts.
This link has all the information you need to know and an example at the bottom of the page that makes me giddy thinking of all the fun possibilities!