Shooting Jehova’s Witnesses wedding is not much different from any other western type wedding. Entire day is very similar to other weddings and I suggest you to check through existing posts to get details on other parts of the day including the Ceremony.
As for the Ceremony, it is happening in the Kingdom Hall (or Assembly Hall) with the elder presiding at the podium in the very front of the Hall. The Ceremony as a ritual is visually very simple. So is the interior of the Hall. Therefore I’d suggest to spend more time on guests and family arrival. Don’t forget shots of the parents and grandparents on both sides.
Discuss with the marrying couple if they want you to record entire Ceremony, or just bits of it to be edited later.
For the former you’d be filming the elder giving a speech, or sermon with possible reaction shots of the bride and the groom. Position your self on one side between the elder and the couple where you can pan your camera left and right.
For the latter, get shots of the couple sitting in front of the elder and listening to him. They may be looking into the Bible and reading paragraphs mentioned by the elder. Vary shots of the elder with reaction shots form the guests. Use wide, medium and close up shots to make the edited copy look better. Use the side aisle to walk to the back of the room to get wide shots.
Exchange of vows and exchange of the rings, and the book signing all are very similar to the Catholic Christian Ceremony.
