The $999 SlingStudio makes it easy to produce multi-camera Facebook Live and YouTube streams

[A] video producer can easily record, edit and monitor feeds from four HD video inputs. While you can connect a total of up to 10 cameras and smartphones (iOS and Android via Sling’s Capture app) to the box simultaneously, the editing software makes you focus on four feeds at a time for the live edit, which is typically enough for most setups. If you do have more than four cameras connected, though, it’s easy enough to switch those feeds in at any time (or play pre-recorded videos). – Frederic Lardinois, TechCrunch