Seeing as Moshe told them nothing new, what is "Viyeda'atem ha'Yom" referring to?
Rashi: It is referring to taking it to heart - to know and to understand, and to accept Hashem's rebuke. 1
Seforno: It is referring to the generation that is entering Eretz Cana'an, who witnessed all the forthcoming list of wonders firsthand, and who should therefore make signs 2 as testimony for the next generation who did not see it, to learn about them.
What are "Gadlo", "Yado ha'Chazakah" and "Zero'o ha'Netuyah" referring to?
Ramban: "Gadlo" refers to where Hashem revealed His superiority; 1 "Yado ha'Chazakah" to where He told Moshe (in Shemos, 3:20) "Veshlachti es Yadi Vehikeisi es Egypt", and to the Yam-Suf where the Torah writes (in Beshalach Shemos, 14:31) "Vayar Yisrael es ha'Yad ha'Gedolah ... ", and "Zero'o ha'Netuyah" to the fact that, from the moment that Hashem stretched out His Hand against the Egyptians, He gave them no respite until He wiped them out at the Yam-Suf. 2
Seforno: "Gadlo" and "Yado ha'Chazakah," refer to Hashem punishing those who rebel against Him. Refer to 11:7:1:2, and "Zero'o ha'Netuyah" to Hashem's outstretched Arm, which was ready to strike again whenever the sinner continued to sin.
Ramban: Where Moshe challenged Pharaoh and said "Hispa'er Alai!". See also, Shemos 8:5, 9:29.
What are the implications of "Ki Lo es Beneichem ?"
Seforno: It implies that they, who witnessed the Musar and the strong Hand of Hashem should create signs for future generations who did not witness them. 1
Da'as Zekenim and Hadar Zekenim: It implies that their children are less liable to be punished than they are, 2 because they witnessed Hashem's chastising and His greatness.
