flash player not playing best available stream when set to "Auto"
here's the stream: http://content.jwplatform.com/previews/DeuwXZ4N-1uGpmv4Y?exp=1447295342&sig=74b498807653db360c3ec3bd1bbb7665
there are 3 available versions, 180p, 450p and 720p
i'm playing on chrome (latest) with flash player 18.104.22.168
the "HD" setting is set to "Auto"
sniffing the network traffic, i see that it's always requesting the 180p segments: http://jwpsrv.a.ssl.fastly.net/content/conversions/oQi4Qizy/videos/DeuwXZ4N-3034181.mp4-XXX.ts
it never switches up to the 450p or 720p versions, and as far as i can tell it doesn't even attempt to download any parts of the other streams.
I'm on a solid 10Mbps connection here, and the 720p version plays great when i select it manually.
why doesn't it switch automatically?