Well, I see there are folks that claim they stream at the lowest resolution even when they've hat their full speed data limit and drop to FAP speeds. You and I likely wouldn't like it, but it does appear to be doable.
Solved: Upgrade to Gen5, can you stream Netflix? - HughesNet Community - 78915
I think it depends how crowded your spot beam is. Around here the beams are so crowded people usually can't stream during prime time reliably even when they're still using priority data and not FAPed. We have a Hughesnet Gen5 and a Viasat Exede system here and neither reliably streams during prime time, although the Exede system seems to do better even though it's only 'up to 12 Mbps' as opposed to Gen5's 25.