Add native lazy loading support for HTML video and audio tags

[adamsilverstein]

Feature Description

Support native lazy loading for HTML video and audio tags when browsers implement this capability.

Adding native lazy loading extends WordPress's media performance improvements to cover video and audio tags as browsers release support. See ongoing work and discussion at whatwg/html#10376.

This feature would:

• Detect native lazy loading support for video/audio tags
• Automatically apply loading="lazy" attributes
• Ensure compatibility and fallback for unsupported browsers

This will benefit publishers by improving page performance for media-heavy content without requiring manual configuration.

[adamsilverstein]

I don't think we are doing this already, but worth checking. Perhaps this also makes sense as a Trac ticket.

[westonruter]

The Image Prioritizer plugin is currently lazy-loading video and poster with JavaScript. So it'll be great to eliminate that in favor of this new web platform feature.