If you run into trouble, we've also expanded the Remote Development extension guide in VS Code documentation to cover Visual Studio Online as well: https://aka.ms/vso-docs/developing-extensions
PM from MS here. Authentication and authorization is managed by a cloud service but your code is not persisted in the cloud. The service optimizes for the most high perf connection possible via an encrypted channel with the cloud being one option. We intend to allow customers to lock down their invite links as well as they so choose.
PM at Microsoft. Beyond co-editing, Live Share enables co-debugging which allows you to track down problems that only happen on one machine in a low latency environment and enable concurrent investigation of different variables or stack points against the same running app. We've got more features in mind to enable end-to-end development. It also follows a model that actually does not require sync'ing at all which gets you up and running fast and improves security.
PM at Microsoft. Thanks for the feedback - we're thinking hard about ways to ensure that the changes that land in your code is only that which you expect. Are there specific features that you'd need before you'd be comfortable using something like this?
PM at Microsoft here. Live Share not only allows you to collaborate in real time in a lower latency snappier environment but also enables you to seamlessly transition from watching to participating, editing, stepping, and inspecting. The difference is you can collaborate but still operate independently which is not possible with something like a screen share. Screen sharing is great when you want to show your entire desktop or show visuals. Live Share lets you add another tool into your tool chest to better enable concurrent collaboration.