Binge On, T-Mobile’s “free” mobile data option for streaming video, will now support YouTube and Google Play. The move comes as the FCC continue to consider whether the option breaches net neutrality rules.

The option means that any video from participating providers doesn’t count towards data caps, effectively meaning there’s no direct cost to the viewer. Unlike some programs, there’s no fee or restrictions for participating providers, but they do have to actively sign up to the program and add a piece of code to their sites.

The downside is that officially the service was only available for content running at a 480 resolution or lower. However, independent tests revealed that unless the customers switches off the Binge On option, T-Mobile is simply slowing down all video content to 1.5Mbps, which makes many sites default to the lower resolution. T-Mobile has now confirmed that’s how things work.

YouTube had been the most high-profile video site not to take part in the program so far, partly because its bosses weren’t happy with the way T-Mobile was handling video data of both services that had opted in to Binge On and those which had not.

It’s now signed up after T-Mobile agreed to several key changes to the way it manages the program. One is that as well as asking to take part, sites can actively opt-out and T-Mobile will not slow their streaming or downloads at all.

Another is that participating sites can choose to manage how they meet the 1.5Mbps average speed limit. That means they could for example provide content at a resolution greater than 480 by using compression techniques.

There’s also a tweak for customers, who’ll no longer need to go into settings menus to switch the feature on or off. Instead they can simply dial #263# through their phone keypad to start BingeOn and #266# to return to their normal metered usage.

Whether that’s enough to satisfy the FCC remains to be seen. While officials there have previously praised BingeOn as a customer-friendly innovation, and while there’s no commercial bias towards any particular customers, the simple act of excluding some internet traffic from data caps but always metering other traffic (such as audio streaming or webpages) appears to violate the principle of net neutrality.