[html5] Autoplay and preload insufficient for proper video playback.

[Marques Johansson]

This attribute fits in with what I was requesting last week.

My server provides a pay-per-minute video-on-demand service.  I don't
want the browser to request more than I am going to send it and in
HTTP I have no way to tell the browser to use "Range: bytes 0-1000",
let alone "Range: 0-" (which my service would refuse to serve).   My
service would set the buffer attribute to an acceptable amount of time
that my service would essentially be giving the user for free
(something we already have to do in our Windows Media world).

Along with this attribute, attributes to set the max fetch size and
the fetch style would serve my purposes very well.

<video buffer="5000ms" partialrequestsonly maxpartialrequest="10000">

These are horrible attribute names, but something like this would
avoid needing to change the HTTP spec to get the browser to use
"Range:" in requests and to set the upper bound for ranges.