"The school is aware that sharing video can incur large data costs however where students are connected using a common ISP (Internet Service Provider) as the school this will reduce the cost to almost nothing. There has also been demand for French TV and an application is currently in progress to very soon be able to push out this out to schools on KAREN."
I wasn't aware of any ISP who discriminated in favour of intra-ISP traffic.
UPDATE: "SNAP offered free home to school traffic."
in reference to:
"KAREN » NEN Evaluation Project"
- KAREN - NEN Evaluation Project - Christ's (view on Google Sidewiki)