3.14.x Medias

3.14.7.1 [1]
3.14.8.1 [2]
I suggest removal of the exact listing of the media types, specifically
3.14.8.1 [2] where a "must" is stated.
The media types depend on the UA and its environment.

3.14.9.4.14 [3]
The intention of
"5. These steps must be aborted."
points is unclear to me.
If the paragraph describes an algorithm with hierarchical nested "if"s,
then the formatting should be changed.

350ms (+/- 200ms) - shall we include such values directly?
I assume those values are based on some UX study.
Could anyone provide some background information why these and not other
values are specified?

Why in the next line the time is given as text "three seconds" instead
of "3s"?
IMO one convention would be more consistent.

3.14.9.6 [4]
[...] at least a little [...]
This is too vague and contrasts with the milliseconds and seconds in
previous paragraphs.

[1] 3.14.7.1 http://dev.w3.org/html5/spec/Overview.html#video0
[2] 3.14.8.1 http://dev.w3.org/html5/spec/Overview.html#audio0
[3] 3.14.9.4.14 http://dev.w3.org/html5/spec/Overview.html#loading
[4] 3.14.9.6 http://dev.w3.org/html5/spec/Overview.html#the-ready

.Marcin