The text of A Short Discourse of the English Stage is in fact a re-elaboration of the Preface to the Reader prefixed to the pastoral Love's Dominion published in 1654 and presented as "a Pattern for the Reformed Stage". The ideas of the Preface were favorably accepted by Flecknoe's patrons, William and Margaret Cavendish, and the author decided to re-elaborate them in Short Discourse of the English Stage published in 1664, along with the pastoral of 1654, with the title: Love's Kingdom: A Pastoral Trage-Comedy. Not as it was Acted at the Theatre near Lincolns-Inn, but as it was Written, and since Corrected by Richard Flecknoe. With a Short Treatise of the English Stage, &c. by the Same Author (London, printed by R. Wood for the author, 1664). Both the pastoral and the treatise were dedicated to William Cavendish.
In the text, Flecknoe underlines the need for a reform that will restore English theater "to its former splendor" and dwells on the excellence of Burbage's acting.

LATER EDITIONS:
New edition of 1664 text: London, printed for Simon Neale at the sign of the three Pidgeons in Bedford-street in Covent-Garden, 1674. 

The Discourse of the English Stage was also published in: W.C. Hazlitt, The English Drama and Stage, The Roxburghe Library, 1869, pp. 275-281.
Online text: INTERNET ARCHIVE

RECENT EDITIONS:
Reprints of the edition of 1664:
- New York, Johnson Reprint Corp., 1972 (Introductory notes by Peter Davison). Includes Historia Histrionica (1699) by James Wright (see).
- New York, Garland Pub., 1973.
- in Critical Essays of the Seventeenth Century, edited by J. E. Spingarn, Oxford, Clarendon Press, 1908, vol. II (1650-1685), pp. 91-96; Elibron Classics, 2001 (unabridged facsimile of the edition published in 1908).
Online text (1908 edition): INTERNET ARCHIVE
- in Augustan Critical Writing. Edited with an introduction and notes by David Womersley, London, Penguin, 1997, pp. 3-7.