Unofficial app for legacy Samsung SmartTV's which plays Twitch live broadcasts.
Official Samsung instructions
You have to run some kind of web server or a specific app for installing SmartTV apps like SammyWidgets.
On your TV, go to Menu->Smart Features->Samsung Account and type name "develop".
Then go to SmartHUB, click "More Apps" button, then click "Options" button and choose "IP Setting", put the IP address of your web server and finally choose "Start App Sync" option. Twitch app has to be installed now.
For 2014 models "More apps" button might be absent, if so try: long press the enter button on any app, then the menu will pop up, select IP Settings, put in the IP, then long press enter again and then Start User Apps Sync.
For models released before 2013 you might want to use these instructions instead: From the SmartHUB main screen, click the "Tools" button on the remote. Only from the "Tools" menu, navigate to "Settings", and from there to "Development". (You still have to be logged in as 'develop')