MacRumors reports that Build 10A5376e has arrived three weeks after iOS 6 beta 3, alongside Xcode 4.5 Developer Preview and Apple TV Software Beta 4.
As well as the removal of the dedicated YouTube app, Apple has added a WiFi Plus Cellular toggle in the Settings menu, which will allow apps to automatically use your mobile network when the WiFi connection is weak.
Apple's new Passbook app has seen the addition of an App Store button on the welcome screen in iOS 6 beta 4. The report notes that the button is not currently active, but indicates that Apple will use the button to direct users to a dedicated Passbook compatible app section of the App Store.
In the Privacy menu in Settings, Apple has added Bluetooth Sharing to the list.
Some minor bugs have also been fixed in the new build.
iOS 6 is set to be released this autumn, probably alongside the iPhone 5, which is expected to launch at a special event on 12 September. The new mobile operating system will bring more than 200 new features to iPhone, iPad and iPod touch, including the introduction of Siri to the iPad, a new Maps app, and more.