<< Suggested Windows-Media-Player Error-Message ( not present in version 10.00.00.3646 ) >>
IF the user tries to drag the scroll-thumb, AND the WMP cannot do this because the index-block evidently missing from the end of the file, due to a truncated download, THEN WMP might, in addition to snapping the scroll-thumb back to the current position as it does, also display an informative message-box "Tail-block missing from file, probably an interrupted download, can't re-position".  Less elegantly, the play-speed-menu might be extended by an additional entry to explain why the speed-entries are grayed out in a brief menu-entry-sized set of words "Speeds not available - file corrupt", and then if you click on that entry, the lengthier explanation is available.

This issue also motivated the brainstorm of the transcript-pane and that still seems like a cool idea - maybe y'all really COULD do that in a couple of days.

<< Loosely-Coupled Synchronized Transcript Pane ? >>
Given the unimaginable XML code-base you have in-house, to an outsider it seems it must be a weekend's work ( how many times have I thought that ... ) to fry up a trancript-capture editor that would automatically tack the time in there every few words, using invisible mark-up.  So clicking or double-clicking on a word would reposition the video to that point, and just letting the video run would autoscroll the transcript. 
Marketing-wise, I am not all that busy, but I'm never going sit through that "RICO PERF" video at normal speed, even though there are probably sub-sections I'd be interested in, via the overview of the trancript-pane.  At the corporate level generally there are obviously people who value their time even more highly than I do - for them, to be able to scroll through a transcript pane and sit through video only at points which interest them - this would add value to their internal corporate presentations too. 
WMP-SDK or not, obviously internally Microsoft has an interface to get-and-set the video-position(even for hi-res video), so the transcript-pane could simply be a separate process for the initial Channel-9 Beta anyway.
The transcript being external it could be translated into other languages - in particular the nice tours of the Microsoft Hardware Labs would have a wider audience this way, the video does add value to the words, you want them synchronized.

        Always the big ideas,
         PG