Today, alongside iOS 9 developer beta 5, Apple has released their 5th developer beta of watchOS 2 to all developer account holders. more than 2 weeks after we saw the launch of watchOS 2 beta 4.
“watchOS 2 requires the iOS 9 beta to be installed and can be downloaded over-the-air using the Apple Watch app on the iPhone by going to General –> Software Update. Caution should be used when installing this beta, as downgrading the software on the Apple Watch is not possible.” – Mac Rumors
watchOS 2 Beta is currently only available to developers, so no one signed up with the public beta program can get their hands on it.