How can I control how much data Netflix uses?

I thought that cellular Internet might one day subsume residential Internet but perhaps not:

"Watching movies or TV shows on Netflix uses about 1 GB of data per hour for each stream of standard definition video, and up to 3 GB per hour for each stream of HD video. This can create headaches for Netflix members who have a monthly bandwidth or data cap on their Internet service. Below, you'll find a few ways to reduce the amount of data Netflix uses, without having to resort to drastic measures (like actually watching less Netflix).

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)"

https://help.netflix.com/en/node/87