In custom filter, add the extension type you want block. E.g. .mp4 .mkv .flv It can even block external fonts (bandwidth's not cheap for me) I would have

In custom filter, add the extension type you want block. E.g. .mp4 .mkv .flv It can even block external fonts (bandwidth's not cheap for me) I would have given you a step by step tutorial but my PC is down ATM.