I think you have two options:
-move schools
-talk to his current school about this.
I speak from experience as I was in a similar position to you a few months ago with my dd. Fortunately for her the video did not get passed around, but everyone knew what she had done. She did not want the school to know what had happened but in the end they found out anyway, and were really amazing and supportive. The perpetrators were dealt with severely and dd was given support and counselling to deal with the bullying and the lack of self-esteem which lead to the incident in the first place.
I completely empathise with how you are feeling; I felt my world had fallen apart. But in the end I wished I had gone to the school straight away, it would have nipped the bullying in the bud and saved weeks of extreme angst for dd.
I really think doing nothing is not an option. This will not go away on its own. I completely understand how your ds does not want his school to know, but honestly they deal with this sort of thing alot (although this seems like a particularly bad case to me). At the very least your ds will need support to face his schoolmates again. He can't stay home forever. And as someone else pointed out, this is abuse and the abusers need to be made to stop.
If you really can't face the school then it would seem you have no option but to move away. However from my own experience, although of course I wish it had never happened, at least my dd has had a valuable lesson in actions and consequences, and by facing up to her school mates she has become a very strong person, and also learned not to judge others in the way she herself was judged.
I wish you well, you will need strength and love to support your ds through this - and it sounds like you have plenty of both.