For its progress bar, oTranscribe currently uses a neat little library called Audio.js. However - as the name implies - this only supports audio files, and comes with a bunch of features not used in oTranscribe.
MIT-licensed and just 2.87kb minified, Progressor.js can be used to create lightweight, stylable, scrubbable progress bar for
<video> tags. Demos and usage instructions can be found on GitHub.
As of v0.2.1, I consider it production-worthy and will be rolling it out to oTranscribe (along with video support) soonish. If you happen to use it in your own project, I’d love to know.