In this CTF challenge, you need to find the flag in FLAG-XXXXX format. The challange is simple. We have a video with an encodded secret flag inside. Scripts and utility usages are allowed. No need for codding.
Have a nice challenge!
Have you noticed that there are some weird parts suddenly seen on the screen? I'd stop, and investigate on those parts.
If you would follow the step in the first hint, you'll see that the challenge wants you to continue with sound part. What does it mean to have ".1" in 5.1 or 2.1 sound modes? I bet that the flag is somewhere around there.
That ".1" channel has some kind of pattern if you investigate it. Is it a AM, PM, or FM? Firstly find the modulation. Then, you can encode the secret flag inside.