To get pictures/video of this most interesting behavior, I'd suggest setting your camera up on a tripod and after making sure that it is aimed properly, just let it become part of the scenery. Then at random times as you pass by, take a quick picture or turn the video on for a few seconds/minutes even if they aren't engaging in this behavior. Because if you just leave the camera handy and try to take pictures of them when they are discussing their day, just as you are ready to take a picture, they'll stop and do something else. Then you'll put the camera down and they'll go back to doing what what you want the picture of and stop when you try again to get the picture. This will give them a chance to get use to seeing/hearing the camera and to ignore it.
If they have a set time for doing this, then you could try turning the camera on a few minutes before they start and turn it off after they are done. They might be less likely to notice it and be more interested in conversing with each other.
Good luck and I hope you can get some videos of them, it sounds like it would be really funny.
Spotted Pony