I have a picky client who is complaining that certain people didn't make it into the wedding video. None of these people were part of the wedding party. Is this my problem? Obviously I try to get as many people in as I can, but I wasn't preped before hand on who was essential outside of the parents of the couple and the wedding party.
This is one of the many reasons I don't do wedding videos except for free as a favor to a family member. The only solution I can see would be to get copies of still photos of the "missing' people taken by the bride's photographer; scan them into your computer, add some moves and dissolves, and voila!
Also, shoot more b-roll next time, "spray the room" at intervals, just to cover such eventualities, you might leave it off your master but keep it for insurance... If you had arranged for the bride/groom to give you a checklist of special people, you're off the hook for anybody not on their list, but not really, since they expect you to get, well, *everything*.
This is a reason I would always shoot receiving lines as well as try to get a candid few seconds of every reception table early in the evening.