I saw it when I was at Bethel in New York after I graduated from MTS. It says that pictures should be in good taste, taking into consideration other cultures. Bethelites should be used for photos, or a local family with their children may be used if they are approved by the Congregation Service Committee. It should be clear in the photo who is "doing the talking or teaching." I think thats why in so many of the photos, the person who is apparently "preaching" is making some kind of hand gesture.
BF