"A lot of film has been found, most likely from the third [black box]. The entire film is collected in a bucket and handed to the military," the source said Thursday.
The source said earlier that the third recorder has not yet been found. The first black box was sent to Moscow for decryption on Tuesday, while the Defense Ministry said Wednesday that a third black box has been lifted from the seabed.
The Tu-154 heading from Moscow to Syria crashed shortly after refueling and take-off from the Russian southern city of Adler, near Sochi, on Sunday.
It was carrying 92 people, including eight crew members, 64 musicians of the Alexandrov Ensemble, nine reporters, a renowned charity worker, and two federal civil servants.
A law enforcement source said Thursday the main phase of the search and rescue operation was over after all main fragments and 19 bodies have been recovered from the Black Sea.