I was coming here to post that the chap.16 video was no longer available. Apparently that was posted in Oct.2016? I thought the walkthroughs had quality standards.
Edit: Here, Chapter 16 collectible walkthrough for the achievement only.
This is my video, I just recorded it after using the walkthough to locate the egg/light thing. Feel free to use it for any and all walkthroughs for any version of Limbo or any achievement guides.