Use another device: While not possible in every case, you may wish to try using a Windows computer, or potentially a different Mac (as different graphic chipsets may exhibit different behavior). This means that any colorspace adjustments need to be done by the source device, which in this case, means the Mac computer. When receiving YUV, the BoxCaster simply uses the color values it receives over HDMI and doesn't adjust them in any way (other than to compress the images using h.264). This is a known issue with certain Macs with certain graphics chipsets. Some Mac computers choose the YUV colorspace, but don't properly map their screens' RGB pixel values into YUV. Windows computers typically choose the RGB colorspace. Cameras and other native video devices (like video mixers) typically choose the YUV colorspace. The BoxCaster is able to receive video from HDMI sources in two different colorspaces, RGB and YUV.
Some other Mac computers appear fine, as do Windows computers, cameras, video mixers, etc. Some users experience a discoloration when outputting HDMI (either directly or via a DisplayPort or Thunderbolt converter) from some Mac computers into the BoxCaster.