ISSUE-147 (playbackrate-undefined): Chairs Solicit Proposals

'playbackrate: undefined behavior when the user agent can't play back at 
the requested rate'

Per the decision policy, at this time the chairs would like to solicit
volunteers to write Change Proposals.

http://www.w3.org/html/wg/tracker/issues/147
http://dev.w3.org/html5/decision-policy/decision-policy.html#escalation

If no Change Proposals are written by February 6th, 2011 this issue
will be closed without prejudice.

Issue status link:
http://dev.w3.org/html5/status/issue-status.html#ISSUE-147

- Sam Ruby