I cannot vouch for the absolute validity or authority, but I found the following at http://www.mninter.net/~blkeagle/hats.htm.
"The red beret was introduced originally as part of the Leadership Corps uniform in 1971. The Leadership Corps, as rolled out then, were the forerunner to today's Venture Crew -- three or more boys aged 14 or over, whose jobs it was to work with and advise the Troop's elected leadership, while training and coaching younger Scouts and continuing on their advancement. Leadership Corps members wore the kelly green Scout shirts with special "SCOUT BSA" strips (that's what we were calling ourselves back then...SCOUTS and SCOUTING/USA). In 1973, the red beret was extended for wear by ALL Scouts if the Troop's leadership (that is, the YOUTH leadership) elected to wear it.
The beret has NOT stopped being official, Henry. "As long as the hatgear is decided upon by the Troop's membership and leadership, it may be worn if you can obtain them. This not only goes for the red beret, but also for the "floppy ears" hat, the Campaign ("smokey the bear") hat, the flat Scout hat (in the military we called it "the overseas hat") and seven other hats that the BSA has rolled out for it's youth and adults to wear over the years. "