If a piece of text was added onto the page, stating that "video controls are revealed on mouse over and keyboard focus", should this pass the SC?

I hadn't considered that scenario before, but I think that would count as:
"information needed to identify that user interface components are available is visible"

I'll raise with the COGA folks who lead the SC development.

Thank you @benja11y for the thoughtful feedback.

Where is the quoted bit controls are not considered a process in terms of this SC from exactly? I am not finding that in Understanding (stable or editors versions). That bit does seem awkward to me, but I think I need more context. I am also not clear regarding what changes you are recommending? Or are you just asking for clarification regarding the new proposed SC?

@alastc it certain has face validity that text instructions about mouseover or tabbing would count as information needed — so thanks very much for circling back to the COGA folks.

coga feels that it need clear how to reveal hidden controls.
Clear: can be "more" icon with text or personlization sematice.
Clear instruction on how to reach the control, that are on the page before or adjacent to the control is enough

AGWG response:

@benja11y a number of changes have been made to the Understanding document since your issue was opened 5 months ago. For example, the passage you cite has now been modified to read:

Information needed to identify user interface components is usually the component itself; however, there are situations where controls are not visible. Complex components such as video players and carousels often include controls that are visible on hover. The presence of the complex component — for example, the carousel component or the video image — provides the “Information needed to identify the user interface components.” For a carousel, controls displayed on hover should also be displayed when the carousel is activated. For a video player, activating the video image should launch the video (sometimes in a new window), at which point more video player controls, including controls displayed previously on hover, should be visible. Some users may still struggle if video controls are not persistently visible, so there is benefit to providing a mechanism that allows users to have the controls persistently visible.

We believe such changes address some of your concerns with misinterpretation.

Your second question asked if text instructions could be used to meet this requirement:

If a piece of text was added onto the page, stating that "video controls are revealed on mouse over and keyboard focus", should this pass the SC?

You were concerned that text instructions would not meet the "equivalent component" wording of the first bullet. However, as @alastc points out, the preamble of the requirement itself allows text instructions to be sufficient:

...information needed to identify that user interface components are available is visible...

@lseeman pointed out in a response that the identifying information should be clear.

Obviously there is a degree of interpretation here, both in what is "needed to identify" and what is "clear". Authors concerned with differences of interpretation can seek to ensure hover or focus are never the triggers for making components visible, or that a mechanism exists to make the components persistently visible.

@alastc please review #2125 Although I think the logic for the change stems from my work to create an official response to this issue, the issue does not specifically call out this need to reword the bullet. So if necessary, I can open a separate issue.

The response above was accepted, and there is a separate PR that has updated the SC text.