That's easy. Not all view points are equal The view point which takes rights away from a group by another group not shown to benefit is bigotry. Even when another group benefits that benefit needs to be weighed at the cost of the restriction.you think that the "shit" I believe is "utterly ridiculous"???
Not allowing you to murder might infringe on your desires, but is better for others as a group.
Disallowing you to marry a minor my also infringe on your desires, but is better for the group as a whole.
Disallowing two adults to marry regardless of gender hasn't been shown to infringe on the rights of the group in any way. Now you can point to the increased out of wedlock births the original video claimed, but I've already completely debunked that.