The Electronic Frontier Foundation has taken a thorough look at T-Mobile's new Binge On feature, which lets customers watch video from Netflix, HBO, Hulu, and others without it counting against their data plan. And while some customers may appreciate the new perk of choosing T-Mobile, the EFF is decidedly unhappy with the whole thing. First, the EFF has found that T-Mobile isn't "optimizing" any of the video served to people using Binge On; instead, the carrier is merely "throttling the video stream’s throughput down to 1.5Mbps," which can lead to stuttering and a generally awful playback experience if the clip you're trying to watch is higher quality than 480p.

T-Mobile's Binge On partners send "DVD-quality" video to users, but the carrier itself is throttling all video — even if you're downloading something to watch it later, according to the EFF's tests. It doesn't matter if a video provider is enrolled in Binge On; if you've got the option switched on (and it is by default), then any HTML5 video you try to watch will be slowed down. "Our tests show that video streams are capped at around 1.5Mbps, even when the LTE connection and the rest of T-Mobile's network can support higher throughput between the customer and the server," the EFF wrote in a blog post. "In other words, our results show that T-Mobile is throttling video streams, plain and simple."

Customers have the option of disabling Binge On and seeing videos as they normally would, but T-Mobile's approach to the whole thing has compelled the EFF to call for the FCC to investigate the matter. (That's something the commission could already be preparing for.) "It’s pretty obvious that throttling all traffic based on application type definitely violates the principles of net neutrality." T-Mobile has disagreed with the term "throttling," instead favoring words like "downgrading" to describe what Binge On does to all video displayed on a user's device. CEO John Legere didn't directly address the EFF's findings today.