The email they sent also suggests that the carrier is instead optimizing the videos for mobile. “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.”
All of this stems from T-Mobile’s recent Binge On program which basically allow users to stream videos without it eating into their data allowance. The only downside to this is that video quality has been lowered, presumably so that it takes up less data and so that it can load faster for users, thus preventing the network from being too congested.
That being said, it is understandable that T-Mobile might be a bit defensive about accusations of throttling. The FCC is currently keeping a very close eye on companies who offer similar sponsored data programs over concerns that it might violate net neutrality. However T-Mobile should not have anything to worry about as the FCC had previously praised their efforts and called Binge On a highly-innovative product.