Remove buffered from attributes in <video> element doc

[alattalatta]

What was wrong/why is this fix needed? (quick summary only)

Remove buffered from attributes since it is not a content attribute.

MDN URL of the main page changed

https://developer.mozilla.org/en-US/docs/Web/HTML/Element/video

Issue number (if there is an associated issue)

None.

Anything else that could help us review it

I must have missed it in #5033. 😓

[github-actions]

Preview URLs

• https://pr5151.content.dev.mdn.mozit.cloud/en-US/docs/Web/HTML/Element/video

Flaws

None! 🎉

External URLs

URL: /en-US/docs/Web/HTML/Element/video
Title: <video>: The Video Embed element
on GitHub

• https://developer.apple.com/library/archive/documentation/AudioVideo/Conceptual/AirPlayGuide/OptingInorOutofAirPlay/OptingInorOutofAirPlay.html (1 time)
• https://drafts.csswg.org/css-values/ (2 times)
• https://github.com/whatwg/html/issues (1 time)
• https://html.spec.whatwg.org/multipage/embedded-content.html (2 times)
• https://html.spec.whatwg.org/multipage/media.html (1 time)
• https://w3c.github.io/aria/ (1 time)
• https://webaim.org/techniques/captions/ (1 time)
• https://wicg.github.io/controls-list/html-output/multipage/embedded-content.html (1 time)
• https://wicg.github.io/picture-in-picture/ (1 time)
• https://www.w3.org/TR/UNDERSTANDING-WCAG20/media-equiv-av-only-alt.html (1 time)
• https://www.w3.org/TR/UNDERSTANDING-WCAG20/media-equiv-captions.html (1 time)
• https://www.w3.org/TR/html-aria/ (1 time)
• https://www.w3.org/TR/remote-playback/ (1 time)

[alattalatta]

Made a PR to BCD as well: mdn/browser-compat-data#10571