Install FFmpeg with homebrew. You'll need to install it with a couple flags for webm and the AAC audio codec.
brew install ffmpeg --with-libvpx --with-libvorbis --with-fdk-aac --with-opus
I recently had several days of extremely frustrating experiences with service workers. Here are a few things I've since learned which would have made my life much easier but which isn't particularly obvious from most of the blog posts and videos I've seen.
I'll add to this list over time – suggested additions welcome in the comments or via twitter.com/rich_harris.
Chrome 51 has some pretty wild behaviour related to console.log
in service workers. Canary doesn't, and it has a load of really good service worker related stuff in devtools.