The EFF is having a hairball about this, but I think it's the most reasonable proposal for zero-rating I've seen so far.  The biggest problem I can see is apparently each video provider has to register their site separately if they want to be zero-rated, even though (apparently?) they're throttled either way for customers using the feature.  I think it should be one or the other.

https://www.eff.org/deeplinks/2016/01/eff-confirms-t-mobiles-bingeon-optimization-just-throttling-applies