The youtube link seemed like a troll. The other link loaded for a bit and then gave an error about the page not redirecting properly.
We also noticed the url became
18.html and that until now it started from 1 and kept trying to load the page with the next number up. So we went to
Again it loaded a few pages and stopped. We kept doing this until on page
40.html the text
The flag is here! check the response :) was printed on the screen.
At first we didn't see anything in the response, but then we noticed an odd parameter in the response headers:
Alternatively, you could run:
curl -i -L -c -D http://one.challenges.bsidestlv.com:8081/.
The final response will be: