Steps to reproduce the problem:
1. Make sure Data Saver is enabled
2. Have a binary array containing the video
3. Create a blob using URL.createObjectURL(new Blob([...]))
4. Set the muted attributed to true and load the video
5. Invoke play() on the video

What is the expected behavior?
The video should play because it's already in memory and Data Saver wouldn't save a single byte by not playing it.

What went wrong?
The browser ignores the fact that video is fully loaded and refuses to play the video.

Did this work before? N/A 

Does this work in other browsers? N/A

Chrome version: 59.0.3071.115  Channel: stable
OS Version: 10.0
Flash Version: 

Data Saver setting is irrelevant if the data is already fully loaded, therefore there is no reason not to play the video.