Sorry I'm getting to this so late. Discord is an app for your phone/tablet or PC. I believe it has a web interface as well, but most folks install the app on whatever devices they intend to use while watching the games.
https://discordapp.com/ is the link to get the Windows Application. You can get the phone/tablet app from either the Google Play Store for Android or the App Store for Apple iOS devices.
If you've already figured all of this out, I'm sorry I didn't read this sooner. Discord has improved functionality, portability(multiple ways to use it) and lower overhead than Flashchat has.