I have a hotspot device 6 gig plan and binge on, store said youtube is not on binge so youtube should be a hd quality? T-Mobile 4G LTE HotSpot Z915, is this true? since youtube is not on plan, data will count against cap then?

i never got an offer for discount rate>? is the discounted rate for all for 6 month or invite only? just called them and they have no idea on any discount rate...