[sheenobu]

Caveat: I'm not a security researcher just have a basic knowledge of the terms and techniques you would find in a beginner exploit tutorial.

These types of exploits are usually specially crafted files that trick the code responsible for parsing and displaying the video file into running whatever the creator wants. The terms "buffer overflow/underflow+" and "shellcode" might help narrow down a definition for you. Below is an overly simplistic version .

The video might contain, inside of it, a specially written computer program that sends the IP address of the current computer to whatever location the attacker wants. (This is the shellcode). This code could be really simple.

The video could also have parts in it that do not make sense. the video player code makes assumptions about the video that the video purposefully violates. When the video is processed by the computer, the video player code misunderstands what it needs to do and will accidently treat the video as code. (this is the buffer overflow). Since parts of the video are actually special shellcode, the computer has been tricked into running code hidden inside the video.

The article below implies that is what this was https://www.vice.com/en_us/article/gyyxb3/the-fbi-booby-trap...

+Buffer overflows / underflows are just one of many techniques for exploiting a program. it's the main one I know in passing.