BrowserSync does not require a browser plugin to be installed. This is because it serves the files directly itself, and uses a script which opens a socket between the browser and the server.
It is not constrained to a single device, it works across desktop and mobile devices at the same time. It will update code changes, synchronize scroll positions and form inputs automatically across all browsers and devices.
Browser-Sync has been tested to work with desktop (Chrome, Firefox, IE 7-10, Safari, Opera) and mobile (Android, iOS, Windows Phone, Opera Mobile, Firefox Mobile) browsers.
Sometimes when setting up BrowserSync in Windows some errors will pop up. Most of the time this is because npm throws errors when trying to compile BrowserSync and some of the dependencies need Visual C++ runtime libraries.
This is easily solvable by installing Visual Studio. Once it's installed, there should not be any more problems.