Aha, from Netflix:
"Adjust your data usage settings
Adjusting the data usage settings for your account is the easiest way to reduce the amount of bandwidth used while watching Netflix. There are four data usage settings to choose from. Each estimate below is per stream:
- Low (0.3 GB per hour)
- Medium (SD: 0.7 GB per hour)
- High (Best video quality, up to 3 GB per hour for HD and 7 GB per hour for Ultra HD)
- Auto (Adjusts automatically to deliver the highest possible quality, based on your current Internet connection speed)
To select a setting that works best for your Internet plan, navigate to the
Your Account page and select Playback settings in the Your Profile section. It can take up to 8 hours for these changes to take effect. Restricting data usage may effect video quality while watching Netflix."