App streaming was introduced last month, as a additional feature inside of Google Search engine. The software allws to stream apps that aren't installed. The app runs on Google servers, only the results are downloaded back to your phone.
From today, we can stream minute-long demos of apps, without actually downloading it. This streaming feature will let you quickly know if the app you are interested in is worth downloading.
This option is not widely available, as its set of advertisers is limited.