: Is the video mostly static or high-pitched noise? That is a primary indicator that the "guide" is hidden in the audio spectrogram.
"NM18.mp4" appears to be a specific video file associated with an or an analog horror series , often used as a cryptic puzzle for viewers to solve. NM18.mp4
: Open the audio from the MP4 in a tool like Audacity . Switch to "Spectrogram" view to see if any images or text have been embedded into the sound frequencies. : Is the video mostly static or high-pitched noise