The Player will only ever download the minimum it needs to function.
So it will download the videos once and then never download them again so long as they are scheduled.
I’ve seen a few cases recently where the Windows Player thinks that it should clean up files from it’s local library that are still in use. We’re collecting information on that issue to fully understand it.
What you could try to see if this issue is affecting you is to turn off deleting old media from the Player library. To do so, find the Player configuration file inside your %appdata% folder (eg c:\Users\username\AppData\Roaming\Xibo…). The configuration file is called xiboclient.config.xml.
Inside that, find the line
and change it to
See if doing that reduces the Player bandwidth usage.