Apple has announced that the native YouTube app that has been with iOS since the very first iPhone will no longer be included with iOS 6. It said that this is because its license to use the YouTube app in iOS has ended.
In light of this, Google will offer its own standalone YouTube app. This is beneficial to Google because it gives the company the opportunity to update the app more frequently and also have more control over the app's features and functionality. Crucially, Google will be able to control how it displays its lucrative pre-roll advertisements. Of course, all this is assuming that iOS 6 users downloads the app in the first place, which we are pretty sure they will given the rich amount of content available on YouTube.
Apple, on the other hand, will no longer need to pay whatever license fees (if any) to Google. It will also save its resources since it no longer needs to develop the app in house.