Here's another old Bryan Magee video where he interviews Myles Burnyeant:
Anyone who's listened to our Plato episodes will find nothing new in this first clip, which is just about who Plato and Socrates were, how Socrates died, and what Plato's dialogues look like. Around 5 minutes in, Burnyeant lays out the evolution from the early dialogues through the more positive middle period (e.g. Republic); this is taken up again in clip 2, around 6:30. Buryeant focuses on the (e.g. epistemological positions) as Plato's most important original contributions. Around 2:00 of clip 3, he gives a formulation of the theory of forms: "that justice, beauty, and the like exist independently of and prior to all the just acts, beautiful things..." He doesn't seem to have any doubts about attributing this theory to Plato (as we did on the 'cast), but he does warn against taking talk of the "world of forms" too literally; it means a set of "invariable generalities," not a world of particular things.
Finally, at 7:05 (still clip 3), the Republic is mentioned. Is justice a benefit to its possessor? Yes, it's the thing we need most of all to be happy. Plato reneges on Socrates's claim that virtue is knowledge; it's more than that: it's knowledge put in control. Magee cuts off the discussion by the end of clip 3, though it comes back as a point of comparison at around 6:30 of clip 4. That clip starts off with a discussion of the later dialogues (the Theaetetus is discussed around 9:45), where Plato criticizes his own past work. This is in accord with one of Burnyeat's earlier comments that the Plato/Socrates project is all about unceasing questioning, not about arriving at answers.
Interestingly, one his final points in clip 5 is that Platonism is much more compatible with modern science (and relevant to responding to the views of materialists) than Aristotle's, even though the latter is more famed for being an early proponent of what's now thought of as scientific thinking.