I think the nanny filmed the kids on their day out to send the parents some impressions of how they’re doing, that they don’t need to worry. It was a private video. Of course, Jonathan immediately thought of easy vlog footage when he received the message with the video and put some music over the nanny talking to the kids. This happens all the time when the nanny takes Andrea to soft play, Alessia on the playground or the kids on walks. Even when the dog walker sends them photos on their walk he uses them as his own. Makes them look like they were actually there with them.