Mash together photos and videos using Lip Swap, which allows you to replace elements of a photo with your own recorded video. Save the result, and share with friends.
Lip swap makes use of the underlying shadercam library - https://github.com/googlecreativelab/shadercam, also written for Android Experiments. This allows easy usage of Open GL shaders with the new camera APIs in Android 5.0 Lollipop. Make sure to check out the source to both and start creating your own shaders and apps today!