Currently, when when a user clicks link of YouTube then they are forced out of the messaging app. Taking over the entire display screen makes, it a bit difficult to multitask, forcing users to switch between active frames. Only the handsets capable of split views can see both the applications at once.
However, the new hyped up feature will make things easy. The feature, which is hidden in iOS handsets from iPhone 6 and above versions, will be activated once it is ready.
This will help users to watch the youtube in chats itself.
Meanwhile, there is no information about the availability of the feature in android devices.