τὸ ἐν κεφαλαίῳ ἕκαστα λέγεις ὑπομνῆσαι ἐπὶ τελευτῆς τοὺς ἀκούοντας περὶ τῶν εἰρημένων;
The commentary translates it as ‘Do you mean reminding the audience in summary at the end of each point involved in what has been said,’ saying that ὑπομνῆσαι takes a double acc. namely, ἕκαστα and τελευτῆς τοὺς ἀκούοντας.
Would it not be easier to understand λέγεις as a command and ἕκαστα as the subject of the infinitive: Do you say that each point should summarily remind the audience at the end of what has been said? I think it is much clearer.
ok, based on what follows, ταῦτα λέγω, this is what I mean, the commentary has it right.