Me and another developer did this on a 300 seat call center on Windows Embedded thin clients probably 8 years ago now. We used timestamps and a high precision javascript library for synchronization. After everybody went home for the night, it would scroll the name of the business and the stats from the day across all the screens until a couple hours before the first calls, then it would load a queued video or text or even just colored lines similar to the windows screen saver depending on the day.