I don't think that Gerry Matatics ever really changes anyone's mind on any issue. He speaks too fast, goes off on many tangents, frequently says he'll put background notes onto his website but never does, and is unfocussed in his presentations.
On the other hand, his talks can be entertaining and, thus, they encourage people to look deeper into various issues.
Gerry Matatics was one of the first people I heard talking that led me to tradition, however, it was Father Wathen's book, The Great Sacrilege, a Conciliar priest inventing new words of Consecration, and the archbishop's utter indifference about it that pushed me out of the Novus Ordo.
Gerry Matatics was one of the first people I heard talking about sedevacantism, but his arguments did not sway me for it was just one person talking and asserting many things to be true which I could not, at first, verify. What actually brought me to the realization of the accuracy of the sedevacantist theory was the reasoned and well-thought out arguments of people such as John Lane and John Daly as well as other personal experiences I have had and witnessed.
Gerry Matatics was one of the first people I heard talking about the "home alone" issue. This is the first time, however, that he seems to make absolutely no sense. I cannot follow his arguments as they seem to be rooted in certain laws and policies that the Church decreed for ordinary times. He does not show, in any way, that the principles he uses to assert his new theory could have applied in every age of the Church, from Pentecost Sunday to the Roman persecutions to Elizabethan England and the Protestant Revolution to the present day. Principles apply at all times, not just when it is convenient to make a case.
I'll continue to listen to his arguments, but I cannot accept his thesis as long as I can see parallels between today and the days of Saint Edmund Campion.