I watched the video He's arguing that it is suspect that people purposefully not voting republican on all races (voting one party on all races was a separate voting option ‘straight ticket’) voted relatively less for Trump. That is not suspect, but actually to be expected, because those people explicitly chose to not vote a straight ticket. (Next to democrats wanting to vote for a republican congressperson they like, they may be republicans that dislike Trump's style, similar to Carly Fiorina, for example.) Furthermore, he says the ‘giveaway’ of fraud is that this is more pronounced when relatively more people vote a straight ticket in a precinct. Also that is not unexpected, as they are relatively speaking more strongly self-selecting to not vote a straight ticket. Finally, the way he presents the data, plotting percentage points (percentage differences) versus percentages is bad practice, because the percentages subtracted from each other correspond to different total numbers (1 percentage point for the first population may correspond to, e.g., 100 voters and 1 percentage point for the second to 10 voters). My impression: this is a biased analysis and the guy is misleading himself at best, but may be cynically doing it on purpose.
BTW, the “MIT data analyst” just has a bioengineering PhD from MIT, but is not associated to MIT. Furthermore, he is the “I invented email” guy: https://en.wikipedia.org/wiki/...