Ditto! They seem to know when a camera is being shoved in their face. All smiles, until you want to take a photo. It goes double for the video. Very happy and smiling even giggling and then you bring out the video and all of a sudden they become very camera shy. But there are ways around it and that is fun, too. We set up the camera so it's focused on the baby and then we play peek-a-boo. It usually works. Or we wave, etc. Whatever gets them to smile or laugh.
It's all fun. But, take out shares in Kodak because it takes a lot of photos to get one you're happy with.