It’s called Game Capture HD and it’s not very good. Since they don’t write drivers for the Mac you have to use their propriety software.
When I first started streaming I use an Elgato HD60. If you have a newer Mac you probably won’t have any USB 2.0 or 3.0 ports only USB-C. My wife streams with her Macbook 13″ Pro 2015 Sierra 10.12.6. I’ll describe how I stream to Twitch using a MacBook Pro 15″ 2015 El Capitan 10.11.6. This article is over a year in the making.
