Mac as digital signage - change current video

I'm working in an environment where we have a Mac Mini connected to a display in a common area. The display is simple - it plays a preset video in Quicktime on a loop.

Iwould like to be able to change that video periodically without 'interrupting' the video on the screen. I.e. I'd like the solution to scan a folder periodically and if the video has changed start playing it. It seems simple in concept but hard to achieve with Googling, which is where I hope the community can help.

So far we have just been remotely connecting to the Mac Mini and downloading the new video and reopening it, but this isn't the most elegant solution. I've also looked at digital signage options but they all seem a bit over the top for what I need.

Thanks in advance!

Elliott