What are the options? Words, deplatforming, authoritative measures, social ostracization or violence?
The first option is the trickiest and most time-consuming but the most necessary I believe. Unfortunately conversation is a lost art online but in the real world it's where you have to put in the most effort and demonstrate with logic and reason.
This is probably one of the most uncomfortable videos I've ever watched and I remember being geuninely chilled throughout. To me it served as a demonstration on how I was completely incapable and unprepared to demonstrably show how wrong and illogical the alt-right are. It served as a catalyst to be someone who can do more than call people immoral or racist.
On the plus side, since watching the video I started to lurk an alt-right subreddit and thankfully 90% of them are genuine idiots. There is constant infighting about if Trump is still one of them or not, are Jews secretly controlling Trump, are conservatives in denial about what they really are, is it okay to race-mix with Asians, are atheists okay, should minorities be allowed to own guns, can gay men be trusted in positions dealing with children, socialism vs capitalism, etc. It's a nice sliver of entertainment considering how insane these idiots are and effectively have no power.