No, full-screen playback can be achieved by connecting HDMI directly to the Flexbox, mirroring the display then creating a multi-output device for the audio.
To select the HDMI input, access the Flexbox input/output settings by clicking the cog icon at the bottom right of your screen viewer when in an active session. Switch your input form SDI to HDMI.
Do I need additional hardware with my remote desktop solution to do full screen playback in Flex?
Updated over a year ago