I've noticed that some video transcodes, and many audio transcodes, list 0 for the final bitrate.
This appears to be an issue with duration calculation.
One such file is https://commons.wikimedia.org/wiki/File:Chiroptera-S%C3%B8ndermarken-cph-2.webm which has a *very* long listed duration because its start/end timestamps are weird.
Others are like https://commons.wikimedia.org/wiki/File:Search-for-2-Adrenergic-Receptor-Ligands-by-Virtual-Screening-via-Grid-Computing-and-Investigation-pone.0107837.s010.ogv which have a listed duration of 0.0s for some reason; most of these are ogg files.
Note these skew the overall results in reportTranscodes.php, though they can be seen easily separated on the upcoming histogram mode.