WhatsApp is testing support YouTube videos inside the app
The developers of WhatsApp is currently testing the ability to view YouTube videos directly in messaging. In other words, the need to open the YouTube app for watching videos can be done soon.
Videos play in an embedded window on the principle of «picture in picture». Available zoom function and fullscreen. You can also hide the playback window, returning to the conversation. Playback also stops automatically if the move to dialogue with the other interlocutor.
While the described functionality is available in iOS on the iPhone 6 and newer. Pro version for Android and Windows Phone information.
Source: GSM Arena