It does it by adding a &list suffix to all the videos in the /video section of a channel. For example:
https://www.youtube.com/user/ESportsTV/videos
Check the URLs to those videos. The link to the first one is:
youtube.com/watch?v=QJKoECZt9pU&list=UUAI86CUHDIkKXGA6YpVBhYg
(https://www. removed because TL automatically converts it into an embed)
Go scroll to the end of that video, and it'll auto-play the next one. And you're gonna have to keep turning off auto-play every time, since Youtube seems to refuse to save that setting.
The only part of the link that's required to watch that video is youtube.com/watch?v=QJKoECZt9pU , but Youtube adds the &list crap because it wants as many hits on their videos as possible, whether you want to watch them or not. This is goddamn annoying.
So if you're as goddamn annoyed by little things like this like I am, here's a solution:
1. Install the Greasemonkey Extension for your internet browser
Firefox: https://addons.mozilla.org/en-US/firefox/addon/greasemonkey/?src=search
For Chrome, you can get TamperMonkey, but keep in mind, I have not tested this script for Chrome:
https://chrome.google.com/webstore/detail/tampermonkey/dhdgffkkebhmkfjojejmpbldmpobfkfo?hl=en
2. Install this Script: https://greasyfork.org/scripts/3433-playlist-remover
Done. No more of that &list crap at the end of those videos, unless you're actually on a /playlists page.
Here, other stuff from me:
http://www.teamliquid.net/blogs/445573-watch-twitch-dm-on-vlc-mpcgood-for-low-end-users
http://www.teamliquid.net/blogs/460199-script-that-sets-youtube-default-size-and-quality
http://www.teamliquid.net/blogs/460015-whitelist-by-youtube-channel-gm-script-updated
http://www.teamliquid.net/blogs/437509-how-to-get-twitch-to-play-on-smarttvs-via-serviio