com.rogers.sportsnet.sportsnet is the application's package name.
com.rogers.sportsnet.sportsnet/com.rogers.sportsnet.tv.ui.AppActivity is specifying an app package and and explicit activity (essentially linking to a specific function).
Unfortunately, the Sportsnet app (com.rogers.sportsnet.sportsnet) doesn't support deep linked content and has no registered url schemes. So specifying sportsnet:// doesn't really do anything. This is why you have to specify an explicit action (com.rogers.sportsnet.tv.ui.AppActivity) just to get the app to open.
At the moment, this is not supported by ADBTuner, but I will add some unsupported parsing of the package/action syntax to make this work for you.
Edit: Just pushed an update that adds the parsing of the package/activity syntax. Give it a shot when you have a chance and let me know if it worked.
