The full name of the documentary and series is "Battlefield S6/E2 - Scandinavia the Forgotten Front". I hope it is not against the rules to post a link to YouTube, if it is just give me a notification and I will remove it. Until there here is a link to the documentary with a timestamp where exactly this is mentioned. I would really much like to read more about these exercises, because before this I had only heard that there wasn't much information known regarding to Soviet military power prior to war with Finland.
That would be the "Great Kiev Maneuvers" of 1935. 65,000 men, 1040 armoured vehicles and 470 aircraft took part in combined maneuvers between the 12th to the 17th of September 1935. This exercise tested out the Soviet "Deep Battle" military theory devised by Tukhachevsky, including the largest formation of airborne troops yet seen - 1188 parachutists landing from TB-3s to capture an airport. The manuevers were conducted by Soviet General Iona Yakir, who was in command of the Kiev Military District, and who was executed in 1937, a victim of the Great Purge. French, Czech, Italian officers were invited as observers. Also among the observers were the future German Fallschirmjäger Commander Kurt Student and British General Archibald Wavell.
John Erickson, The Soviet High Command: A Military-political History, 1918-1941
David Glantz, The Military Strategy of the Soviet Union
David Glantz, The History of Soviet Airborne Forces
Leroy Thompson, Unfulfilled Promise: The Soviet Airborne Forces, 1928-1945