Quoth Jason: 
> I've just written a script which takes source video, adds a common credits snippet to each video, 
> and then wraps system calls to convert to MP4 and WebM. The script also takes the first frame of the video to create a poster image.

Is this a share-able script? That sounds like exactly the kind of workflow-management that I was hoping to find.

(I checked out the AnyVideoConverter that Ed mentioned too. It does a nice job converting files, but it almost seems deliberately designed to be time-consuming. (It will let you generate 3 kinds of HTML5 video formats and outputs HTML code for each of them -- but it makes you do them sequentially, and then you've got to cut and paste the HTML code together, instead of letting you pick 1-3 output formats and generating one tidy code block.) So close...

Ken