For what it is worth, I gave the following advice to a firend of mine who was in a similar position last year,
1. Black the tapes (put the lens caps on and press the record button until the tape is finished and then rewind). This writes timecode to the tape and saves any hiccups at the editing stage.
2. Attend the rehearsal, if there is one. This allows you to get permission from the priest, minister, rabbi etc to film the wedding and gives you a good idea of what is going to happen on the day. It also allows you to check if power points are available. If not invest in extra battery power.
3. Use a tripod. This makes a tremendous difference to overall film quality (less of the wobbles)
3. Use good, uni-directional microphones. This directs sound to the happy couple rather than the motor of the camera (or in my case the heavy breathing of the camera man). Earphones are also useful, this means that the cameraman hears what the camera hears (you'd be surprised how the sound changes when the camera pans - don't miss those vows)
4. Try and film the wedding with two video cameras if possible. This allows 'camera 1' to concentrate on the bride and groom, whilst 'camera 2' can concentrate on the incidental crowd shots (Fairly useful for 'cutaways' at the editing stage)
5. Get some additional footage outside of the church/registration office/synagogue/mosque/whatever. This allows for good intro and title sequence shots.
6. Get fotos (or video) of the bride and groom when they were younger, preferably of a similar age. eg baby, toddler, starting school, with grandparents (this is good for including people in the video who have passed on) and their engagement fotos etc. This is good footage for intro sequences.
7. Don't miss the vows.
8. Don't miss the speeches.
9. I find a good idea is to interview the principal guests and ask them to record their best wishes for the happy couple. This is good for breaking up the end result and is particualrly effective if it is done without the knwoledge of the bride and groom. Also good for including people who couldn't make the wedding (assuming that you can film them outwith or they can provide film).
10. Keep filming. Remember video tape is cheap, memories take a moment and last a lifetime (don't miss them).
11. Cameraman doesn't talk/laugh/cry etc (may be difficult in the unlikely event of an original speech)
12. Have a plan! Yes scribble down a few notes of what you want to film. Have an idea of what you want the final footage to look like. You would be surprised at the difference this makes.
13. Check the lighting and adjust the camera settings accordingly. Video cameras do not (despite what the manufacturers say) perform well in poor light.
14. Enjoy the day, filming a wedding is good fun. Even more fun editing and producing the final video (nerve wrecking too first time round).
Enjoy yourself and good luck
