The Twitch control panel is part of the nodecg-speedcontrol bundle and has not had any modifications from its public version. This panel connects NodeCG to your Twitch channel and automatically updates your stream title and category based on the current run. You can also edit it manually here, and run ads if you're an affiliate or partner.
You'll need to create an application on the Twitch Developers Console to connect Twitch to NodeCG. Instructions can be found in the nodecg-speedcontrol config guide. The very first time you set up a new channel, the panel will be replaced with a "Connect to Twitch" button which you'll need to click to log in. You'll auto log in on subsequent restarts of NodeCG.
From top to bottom, the different elements are:
Logout Button: shows the name of the Twitch channel NodeCG is connected to. Clicking the button will log you out.
Auto-sync: toggle on or off the run auto-sync. When on, whenever you progress to a new run, the Title and Category will update. The Title is based on the syntax advised in the streamTitle entry in the nodecg-speedcontrol config. By default this is: "{YOUR_MARATHON_NAME_HERE} - {{game}} | {{category}} - {{players}}"
The category is based on the Game (Twitch) entry in the run's details. For things like sleep blocks or interviews, you'll want to set that entry to something like Special Events.
Title & Game Directory: the information being sent to Twitch. These automatically update if auto-sync is toggled on. You can edit them if you need something other than your default message,
Update Button: if you manually edit the text fields, you'll need to press the Update button to send that information to Twitch.
Start Commercial Buttons: lets you run the set timed ad break on Twitch - ads start almost immediately after pressing one of these buttons. These buttons only appear on the panel if the connected channel is affiliate or partner.