Booyah is a free mobile video messaging app that integrates with popular chat utility WhatsApp. Once you've installed it, you can simply create video chat conversations with up to 12 other people. You'll be able to choose them from your WhatsApp contacts list, as well as from other messaging and social media apps such as Facebook Messenger or Twitter. Booyah doesn't require any additional registration or login, making it quick and simple to use. Like many mobile messaging apps, though, it's a bit of a data connection hog, so be wary.