They go over how the web and frameworks decided against horizontal, apart from deliberate emphasis, they go over some desktop layout attempts, failures and successes (more of the same vs navigation), a chapter about (paper) documents as the source, and endless panes now using horizontal.

From the description:

Almost every screen we use is a landscape rectangle, wider than it is tall. And on almost all of them, the content moves vertically. Always down.

This video walks through a wrong question. If mobile scrolls down, why doesn't the desktop scroll sideways?

The question turns out to be wrong.

Chapters

• [00:00] Introduction
• [01:23] The Web Could, and Doesn't
• [03:18] The Microsoft Bet - Windows 8 "Metro"/"Modern" failure
• [06:18] What Makes a Difference - Layouts where horizontal works
• [09:14] Horizontal Scrolling as Emphasis
• [10:24] When Horizontal Axis Means Something
• [12:13] The Document Model
• [14:06] The Potential of a Glass Plane

References

• Tim Berners-Lee, Information Management: A Proposal, CERN, March 1989 : http://w3.org/History/1989/proposal.html
• Tim Berners-Lee, HTML Tags, late 1991: http://w3.org/History/19921103-hypert...
• Jeremy Keith, A Brief History of Markup, A List Apart, 4 May 2010: http://alistapart.com/article/a-brief...
• MDN Web Docs, overflow: http://developer.mozilla.org/en-US/do...
• Chen Hui Jing, The horizontal overflow problem: http://chenhuijing.com/blog/the-horiz...
• Beware Horizontal Scrolling and Mimicking Swipe on Desktop: https://www.nngroup.com/articles/hori...
• Responsive Web Design: https://alistapart.com/article/respon...
• Building Windows 8: • Building Windows 8
• Niri Wayland Compositor: https://github.com/niri-wm/niri
• macOS Spaces: https://support.apple.com/en-gb/guide...
• Myspace shows off redesign, promises invites soon https://www.nbcnews.com/tech/tech-new...