MTC is a function that alows you to sync up different scenes and cues to an audio track. Basically in a quick break down, you would have a MTC track playing and it would trigger your audio, video, lighting, and any other devices set up. It does this via a sync code in the track playing. How this works to compu, is you can design a light show and have it triggered externaly at the same time as the audio track. This is really good for when you have, for example, a display that you want to run once a hour on the hour....your MTC would play once a hour and it would sync up the audio and lighting...your display would run...then your last trigger would be a "stand by" look....then a hour later, it would do it again.... giving you the ability to set it and leave it. I personaly use this for halloween and Christmas displays.