According to reports @WABetaInfo notoriously trusted source for news concerning WhatsApp , very early in the messaging app note will be able to play YouTube videos without opening the appropriate application.
For the moment the function is being developed for WhatsApp for iPhone and there is no information concerning the arrival of Android and Windows. However, it seems likely that both platforms can receive the function, which would use the Picture-in-Picture mode.
As shows the short movie below, it should be possible to move the window containing the video, so you can continue reading the text conversation and enlarge or reduce the size of the window. You can also temporarily hide the video, whose play will not be interrupted, however, with a swipe to the right to have full access to the chat below.
The changing of the chat, however, result in the interruption of the movie, but it is a still under development function things could change dramatically before the arrival on the beta version of WhatsApp . Following is a brief explanatory film, while there are no deadlines for the issue to the public.