https://wccftech.com/download-watchos-5-beta-2-tvos-12-beta-2-released-how-to-download/

Developers can now download watchOS 5 Beta 2 and tvOS 12 Beta 2 onto their devices. Here’s how you can get up and running right now.

watchOS 5 Beta is available as an over the air download and if you have the first beta installed you can go ahead and update right now. Simply place your Apple Watch on its charger, launch the Watch app on your iPhone, navigate General > Software Update and then tap on Download and Install.