This one is all about the onetime pad and youtube videos.
If you followed along with part 6 you will have a PDF with some hex, and a collection of hex from badges.
This is the hex from one of the PDF's:
NOTE: you only get to see one of the two PDF's depending on which team you are on.
If you don't know what a onetime pad is then google might help, and wikipedia has a good article about Onetime Pad's
So all we need to do is XOR that hex with some other hex.
The badages have hex, and by now you should have sorted then into a simgle block of hex.
The hex from the badge:
And then we do the XOR:
If we convert the hex to ascii, we get a youtube link: