Typing on a TV with a remote is the worst part of almost any media app. A server address, a user name and a password, entered one letter at a time with a D-pad, is where a lot of people give up, and they give up before the app has played anything. In Yonto Player the answer is a button called Set up from your phone . The TV shows a QR code, your phone opens a page with the same form, and you type on a real keyboard.

This post is about the design: why the two devices talk through a service on the internet and not directly, and why what comes back from the phone only fills in a form.

What you see

On a TV, the forms for adding or editing a source have Set up from your phone at the top. You choose it and the TV shows a QR code, with its address written beside it for a camera that will not cooperate. You scan the code, or open the address in your phone's browser, and a page opens with the same form. You fill it in and choose Send to the TV . The TV's form fills in and says "Filled in from your phone.…