Yes, the tool creates a 720p mp4 as the first step of snatching it from YouTube - it's 751 Kbps video and 112 Kbps audio.
I manually snatched the 720p mp4 from YouTube at the best rate that it would give - 1135 Kbps video and 192 Kbps audio, and then I manually converted that to webm and tried to optimise the compression, so it's somewhat different from the auto-created version on Commons.
As it turns out, my old eyes can't detect any difference in quality between any of the bitrates, so I reckon that Fireogg and your script turn out just as good results as me trying to optimise everything. As I said - nice work!
Cheers
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Rexx