A speech given in a ratifying convention is a weaker indication of original meaning of a Constitutional provision than debates in the Constitutional Convention, and understanding of the common interpretation of the plain words.
It wasn't a mere speech. Those were the written words of the ratification convention in their official ratification document that were voted on and approved by the delegates. The ratification document was the official approval by a state of the Constitution.
In the case of New York, the convention listed statements that were consistent with what the Constitution meant, and Hamilton and future Chief Justice Jay voted for those words. I think what happened was that the Federalists said that a Bill of Rights was not needed, and that since the things the Anti-Federalists were concerned about were not delegated away, they remained with the states. The Anti-Federalists said, OK, then you won't mind putting some clarifying statements in the ratification documents that explain what the constitution means about certain important things. So, the Federalists did. That's speculation on my part, but it explains how such statements ended up in the ratification document.
IMO, those statements are some of the clearest statements of original intent that exist. They simply say what the constitution means to the people who ratified it and in some cases wrote it.
The ratification was not done on the condition that anything (i.e., amendments) be added to the Constitution. At one time the delegates had proposed that the ratification be on the condition that proposed amendments be passed and added to the Constitution. However, NY delegates voted to take out the words "on condition” and replaced them with "in full confidence" that their proposed amendments would be considered.
If the Federalists had backed away from clarifying statements like, "the Powers of Government may be reassumed by the People, whensoever it shall become necessary to their Happiness; ... Under these impressions and declaring that the rights aforesaid cannot be abridged or violated, and that the Explanations aforesaid are consistent with the said Constitution ... We the said Delegates, in the Name and in the behalf of the People of the State of New York Do by these presents Assent to and Ratify the said Constitution" I doubt if New York would have ratified the Constitution. Something like seven or eight Anti-Federalists abstained on the final 30-27 vote and let the state ratify the Constitution.
The proposed NY amendments and "in full confidence" appeared in a separate list after the quote I just provided. The proposed amendments do not include statements about the reassumption of governance. That was in a clariifying statement. In the case of Virginia, Madison and future Chief Justice Marshall wrote the official ratification document along with three other Federalists. The statement that governance could be resumed "whensoever the same shall be perverted to their injury or oppression and that every power not granted thereby remains with them and at their will" was actually from the Virginia ratification document. I attributed it by mistake to the New York ratification document.