I'm no lawyer, but my take on it is that by reproducing this particular value for the validation header, you are stating that you are the Chrome browser. It's likely that this has been implemented in such a way that other browsers could use it too if they so choose; the expected contents of the copyright header can then change depending on what you have in the validation header.
To me, it seems likely that the spec is for a legally defensible User-Agent header.
For "VOD", that works (and is how very simple <video> tag based players sometimes still do it), but for live streaming, it wouldn't – hence the need for fragmented MP4, MPEG-DASH, HLS etc.
It does work for simpler codecs/containers though: Shoutcast/Icecast web radio streams are essentially just endless MP3 downloads, optionally with some non-MP3 metadata interspersed at known intervals.