Thanks very much hus_hmd, very much appreciated.
It's only for very short background videos in my instance, so I don't think bandwidth will suffer. It was mainly about speed of delivery to countries outsite the UK where the pages are loading much slower than in the UK (not so great hosting, hence investigating CDN).
I wouldn't know where to start with creating a filter. Though it's not a good longterm solution, perhaps will look at hardcoding for now.