In the video he never said he was for birthright citizenship. He said it would be hard to argue against it to the Supreme Court and it would be more effective to secure the border. It’s disingenuous to imply that he was for birthright citizenship and now he is against it. He didn’t change his position. He has always been against it.
Excerpts from those SCOTUS rulings:
Elk v Wilkins (1884)
The distinction between citizenship by birth and citizenship by naturalization is clearly marked in the provisions of the Constitution, by which
“No person, except a natural born citizen or a citizen of the United States at the time of the adoption of this Constitution shall be eligible to the office of President,†and “The Congress shall have power to establish an uniform rule of naturalization.†Constitution, Article II, Section 1; Article I, Section 8. By the Thirteenth Amendment of the Constitution, slavery was prohibited. The main object of the opening sentence of the Fourteenth Amendment was to settle the question, upon which there had been a difference of opinion throughout the country and in this Court, as to the citizenship of free negroes ( 60 U. S. 73; Strauder v. West Virginia,@ 100 U. S. 303, 100 U. S. 306.) ...
This section contemplates two sources of citizenship, and two sources only: birth and naturalization. The persons declared to be citizens are “all persons born or naturalized in the United States, and subject to the jurisdiction thereof.â€; The evident meaning of these last words is not merely subject in some respect or degree to the jurisdiction of the United States, but completely subject to their political jurisdiction and owing them direct and immediate allegiance. And the words relate to the time of birth in the one case, as they do to the time of naturalization in the other. Persons not thus subject to the jurisdiction of the United States at the time of birth cannot become so afterwards except by being naturalized. ...
“[t]he phrase, ‘subject to its jurisdiction’ was intended to exclude from its operation children of ministers, consuls, and citizens or subjects of foreign States born within the United States.â€â€¦Justice Steven Field, joined by Chief Justice Chase and Justices Swayne and BradÂley in dissent from the principal holding of the case, likewise acknowledged that the clause was designed to remove any doubts about the constituÂtionality of the 1866 Civil Rights Act, which proÂvided that all persons born in the United States were as a result citizens both of the United States and of the state in which they resided, provided they were not at the time subjects of any foreign power. ...
Indians born within the territorial limits of the United States, members of and owing immediate allegiance to one of the Indiana tribes (an alien though dependent power), although in a geographical sense born in the United States, are no more “born in the United States and subject to the jurisdiction thereof,†within the meaning of the first section of the Fourteenth Amendment, than the children of subjects of any foreign government born within the domain of that government, or the children born within the United States of ambassadors or other public ministers of foreign nations.
Minor v Happersett (1874).
Additions might always be made to the citizenship of the United States in two ways: first, by birth, and second, by naturalization…and that Congress shall have power “to establish a uniform rule of naturalization.†...
At common law, with the nomenclature of which the framers of the Constitution were familiar, it was never doubted that all children born in a country of parents who were its citizens became themselves, upon their birth, citizens also. These were natives or natural-born citizens, as distinguished from aliens or foreigners…It is sufficient for everything we have now to consider that all children born of citizen parents within the jurisdiction are themselves citizens. The words “all children†are certainly as comprehensive, when used in this connection, as “all persons,â€