Are developers responsible for video full screen mode (Success Criteria 2.3.1)

Hello,


Some of my company's animated videos fail Success Criteria 2.3.1, but only in the optional full screen mode (as provided automatically with HTML5 video). At the default size, as they are presented, the videos pass.


We're using the Trace Center Photosensitive Epilepsy Analysis Tool ( PEAT ) (Version 1.6). The PEAT User Guide says to "Test out multimedia at the size that it will appear on your web site. E.g., if a video will be presented in a small window rather than a full screen mode, then test it at the smaller size."


I just wanted to be sure, would this mean developers are not responsible for full screen mode for 2.3.1?


The only related documentation in the WCAG I could find that mentions viewing modes is in Technique G176, where it says "Users with lower resolution displays or that enlarge or view their screens closely would have a higher risk depending on the viewing distance. To address the needs of this group, G19: Ensuring that no component of the content flashes more than three times in any 1-second period<https://www.w3.org/TR/2016/NOTE-WCAG20-TECHS-20161007/G19.html> should be used since it is independent of screen resolution or viewing distance."

This is basically almost saying that accommodating unpredictable resizing is covered by Success Criteria 2.3.2 instead, which is Level AAA. Does that include a full screen mode offered by the site itself?

Sorry if I am answering my own questions, I just wanted to know definitively. Thanks!!

Brian Stevens