Valve doesn't just want you to watch Dota 2 eSports matches -- it wants you to have a small stake in them. It just released a Dota Pro Circuit app for Android and iOS that lets you win Shards (the in-game currency for Dota Plus members) by predicting the winners of Circuit matches. It's sports betting, just without spending real money beyond your existing subscription.
You'll also find a fantasy sports mode (Fantasy Challenge) that encourages you to create your ideal roster of pro players in return for Shards, and a customized news feed shows how well your favorite teams and players are doing.
The apps should be available everywhere, including as a direct APK download if your device doesn't have access to Google Play. There's no mystery behind this app. Valve clearly wants to give you an extra incentive to tune in, not to mention to sign up for Dota Plus in the first place.