Interviews
The director Peter Hall said that he found playwrights spoke as they wrote. We can certainly recognise Pinter's style of writing in his considered, staccato speech.
An hour-long interview with Charlie Rose:
This British Library Interview with actor and director Harry Burton, was made near the end of Pinter's life.
Plenty of interesting things in this Paris Review interview from 1966.
Documentataries
Nigel Williams's excellent Arena documentary on Pinter. Part 1:
And Part 2:
Two other documentaries on DVD are Pinter's Progress (coupled with his masterpiece The Homecoming) and Working with Pinter.
Articles
Though most writing on Pinter concentrates on his major full-length works, there are some very good, thought-provoking pieces on The Room and The Dumb Waiter. The various writings by Martin Esslin have valuable chapters on these works. In addition:
General
This appreciation by the World Socialist Web Site gives a tidy outline of the life and work.
Bernard Dukore, The Theatre of Harold Pinter (JSTOR), The Tulane Drama Review , Vol. 6, No. 3 (Mar., 1962), pp. 43-54. On themes in the early plays.
Ruby Cohn, The World of Harold Pinter, The Tulane Drama Review , Vol. 6, No. 3 (Mar., 1962), pp. 55-68. Puts the works in literary context.
The Room
The Theatre Archive has interviews with members of the original production of The Room. For hardened theatre historians. The interview with Henry Woolf gives many insights.
Leonard Stone, 'Harold Pinter and the Fragmentation of Working-Class Consciousness' This is a very detailed essay on The Room from an online Marxist journal,
concentrating on the depiction of class.
Article by Iranian academics on Alienation in Harold Pinter's The Room
The Dumb Waiter
A director offers a reading of The Dumb Waiter as a religious parable.
Ruby Cohn, TheAbsurdly Absurd: Avatars of Godot, Comparative Literature Studies , Vol. 2, No. 3 (1965), pp. 233-240. Compares The Dumb Waiter and Beckett's Waiting for Godot.
Radmila Nastic, Realism and Metaphor: Harold Pinter's The Dumb Waiter
Radmila Nastic, Realism and Metaphor: Harold Pinter's The Dumb Waiter