How to block certain network connection on lan?

Purpose : There is a video website, part of which I wanna ban from my lan. Actually I want to update the urls dynamically(i have done that with python). My information : There is a computer(windows7) and a tv(Android inside, plays videos via app). Router access is available, but it limites the number of rules. I have a raspberry pi, if necessary some programs can be running on it. Add : I have seen a Windows network manager software doing this to all devices on my lan via arp spoofing or something like that.

Sorry for my poor English.

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