The drawback to alternative vote is that in practice it's way too hard for a large electorate to actually execute correctly. The sheer amount of added time it would take on election day for people to rank all their preference is a hurdle, and then there's the whole mass of people too stupid to understand how to do it that would bog it all down.
Plurality runoff (in "primary season" at least) would work if the system was reorganized... instead of a bunch of Tuesdays, stretched out over months you could have a nationwide primary day at the start that pairs it down to maybe 3-5 candidates a side. Then you have a break of one month for debates, then you do it again. Then you have a top two and do another break of one month, and then the nominee is one of those two in the final go round.
It would deemphasize "early" states and fix like 99.9% of the problems with caucuses and primaries and all that other broken shit that gave us Trump/Clinton.
To me that method would still lead to the Spoiler Effect discussed in the first video during the latter stages.
Example:
5 Republican candidates: A,B,C,D,E.
The runoff will eliminate the 3 candidates with the lowest votes.
Person X prefers the candidates in this order:
C
B
D
A
E
Based on polls and television predictions, Person X believes D will definitely be one of the 2 moving on but A and E are in a tight race for the second spot. X votes for A to make sure E (his least favorite candidate) doesn't move on in the runoff. If he could have ranked preferences, he would have voted C, B, D.
Say there are millions of people who feel like X. Maybe they prefer B, C, D instead. Either way, if enough people like C or B, C or B would get in ahead of D and X would never have to vote for A or E.
