T-Mo announced that video throttling can now be turned off with the "ONE" plan. I went to compare prices and the fine print still says that day passes are needed:
On all T-Mobile plans, during congestion the top 3% of data users (>28GB/mo.) may notice reduced speeds until next payment cycle. T-Mobile ONE™ video typically streams on smartphone/tablet at DVD quality (480p) unless you add an HD Day Pass or Plus; tethering at max 3G speeds unless you add Plus. Simple Choice video typically streams at DVD quality (480p or better) with Binge On enabled; disable Binge On at any time.
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