Dr. Conrad Murray -- Tell-All Documentary Reveals Shocking Secrets

TMZ has obtained an excerpt of a never-before-seen documentary starring Dr. Conrad Murray -- in which the good doc reveals some very intimate details about the singer ... some of which are not flattering.

The documentary -- titled, "Michael Jackson and The Doctor: A Fatal Friendship" -- was shot while Murray awaited trial for manslaughter ... and features a shockingly candid look at the preparation of the trial, which includes intense fighting between Murray's lawyers.

The movie is being distributed by a company called Zodiak Rights ... which says it's already pre-sold the rights to air the documentary to "major broadcasters around the world."

Sources tell TMZ ... NBC is one of the broadcasters ... and will air the doc in the United States.