I use Livestreamer to download my own VOD files when I dun goofed and break my local recordings. This used to work perfectly, but as I write this, the software is broken due to an update in the Twitch API that enforces authentication.
error: Unable to open URL:
(400 Client Error: Bad Request)
There is a workaround, however; you can hand over a client specific token. Right now, this is the one used by Twitch’s web player:
livestreamer --http-header Client-ID=jzkbprff40iqj646a697cyrvl0zt2m6
This works like a charm. For now.