What were Yisrael referring to when they said "ve'At Tedaber Eileinu ... "?
Ramban and Rashbam (in Shemos 20:15): They said it in connection with the rest of the Torah, 1 which they thought Hashem would convey to them directly (just as He had conveyed to them the Aseres ha'Dibros). 2
Ba'al ha'Turim (based on Makos 24a): After they heard two ha'Dibros from Hashem, they asked to hear the last eight from Moshe. 3
Ramban: Though in fact, Hashem had only planned to convey to them the Aseres ha'Dibros and no more.
Ramban: In fact, they were requesting that Hashem should not speak to them directly ever again, not now and not in the future, and that they undertook to obey the instructions of the Nevi'im who would convey to them the words of Hashem. A request that was granted - See 18:15, 16.
Ba'al ha'Turim (and Pane'ach Raza): The Gematriya of 'v'At Tedaber' (or of 'At') equals that of 'Shemoneh Dibros' (or 'Shemoneh'),
Why did they say "ve'At" (L'shon Nekeivah) Tedaber Eleinu"?
Rashi and Ramban (citing Divrei Agadah): Moshe was complaining that they made him feel weak like a woman by preferring to hear the Torah from him rather than directly from Hashem. 1
Seforno: Yisrael were conceding that to hear the Torah from Moshe was not the same as hearing it from Hashem directly. 2
Ba'al ha'Turim: Yisrael were asking Moshe to convey the last eight ha'Dibros 3 to them in a more gentle manner, in a way that they will be able to bear it.
Rashi: Indicating that they did not want to come close to Hakadosh-Baruch-Hu out of love. Ramban: Hashem informed him however, that their actions were based on Yir'as Hashem, and were praiseworthy, as the Pasuk goes on to explain. See Ramban in Shemos 20:16.
Like woman whose creation was secondary to that of man.