You can mute Keyer and Colour Corrector media effects in the Action Media menu. Muting effect media can be helpful when you want to see what your Action setup looks like without the Keyer or Colour Corrector settings, but not lose any of the settings of the muted media effect.

To mute an effect, press Alt and click the K (or MK) or CC media. The check mark in the field turns black to signify the media effect is muted. To unmute the media effect, press Alt and click the field again.