When you receive a YouTube link and click on it, the video will open within the app itself allowing you to watch the video within the app instead of opening in the YouTube app or browser. The update also users to record long voice messages by swiping up to lock the recording, instead of having to hold down the microphone button. And when you finish recording, simply tap the finger to ends the audio recording and send to the user.
Currently the update is only available to Apple iPhone users but may soon be available for Android users. The update is available as WhatsApp version 2.17.81.