Enormous if factual.

I cannot think of a reason other than fraud that would produce a slope like that. The more republican a county, the fewer voted straight ticket? You would assume that geographic location and makeup would make no difference to how many vote straight ticket. If it was indeed Repubs wanting to dump Trump but still have R house and senate, you would see that in less republican counties as well. You would not see the divergence occurring and linearly increasing with how R a county is

Disclaimer: I haven't watched the video, this post is entirely based on the graphs I've seen screencapped from it