Paywall.
USAToday is covering the story without paywall. [1]
Quick read indicates they aren't 'throttling' they're serving lower quality (e.g. smaller) videos to mobile users so as not to use up their data plan as much while they develop a feature allowing users to select their own stream quality in app.
Seems reasonable enough.
They should have been more up front about it though.
Edit
Ok, now I'm confused. How does this story relate to the existing feature to lower your streaming quality? [2]
1. http://www.usatoday.com/story/tech/news/2016/03/25/netflix-t...