It's an old tactic. And often a very effective one. Connect an opponent with an apparently reprehensible cause or group, and you can, by association, transfer all of the allegedly negative characteristics of that cause or group to your opponent. That opponent is now forced on the defensive, either trying to distance himself or herself from the group, or insisting that the cause or group isn't bad at all. It's a lousy place to be.
In trying to connect Trump with the “Alt-Right,” Hillary is attempting this very tactic. It's not working very well, and some of the aspects of this story are really humorous.
Want to see the level of understanding of the typical Hillary supporter?