T-Mobile's Binge On throttling all video to 1.5Mbps, regardless of source, EFF says

In a series of tests over LTE, trying to stream or download a privately-hosted video via HTTP resulted in bandwidth being capped at 1.5 megabits per second, the EFF noted. This applied even when the video's filename and HTTP response headers were changed to disguise it as a non-video file.

Switching to HTTPS to block T-Mobile from monitoring traffic resulted in regular speeds, in this case over 3 to 5 megabits per second. The gap was much smaller when downloading a true non-video file.

T-Mobile isn't actually optimizing video, but is instead counting on services' automatic downgrading for low bandwidth to ensure smooth streaming, the EFF said. If a video is over 480p resolution and can't be downgraded, it reportedly stutters or otherwise performs badly.

Another concern was that T-Mobile is examining files beyond their TCP and HTTP headers, but in response the carrier said that it has techniques to detect video protocols and patterns without reading their content.

In any case the EFF argued that throttling video across the board constitutes a violation of net neutrality, putting aside issues of whether zero-rated offerings like Binge On should be allowed at all.

When active on a customer's account, Binge On is nominally only supposed to downgrade video from the service's official partners, such as Netflix and HBO, with that content ignoring any data caps. YouTube complained that its videos were being throttled, even though it isn't a partner and its content isn't exempt from caps.

T-Mobile reacted by issuing a statement, claiming that it wasnt throttling YouTube or any other site.

"In fact, because video is optimized for mobile devices, streaming from these sites should be just as fast, if not faster than before. A better phrase is 'mobile optimized' or a less flattering 'downgraded' is also accurate," a representative said.

The problem with YouTube was blamed on a flaw in software used to flag videos exempt from data caps, which the two companies are allegedly trying to fix.