Use binwalk -e to see if there are other files (like images or ZIPs) hidden inside the video stream.
: Listen for Morse code or synthesized voices playing at very low speeds or reversed. To provide a specific solution, could you clarify: video_2018-09-08_12-40-50.7z
: Open the video's audio track in Audacity . Switch to the "Spectrogram" view. Flags or codes are often visually drawn into the audio frequencies (a technique called "audio steganography"). Use binwalk -e to see if there are