Mobile using extreme amout of data on one night

[Bayside]

Hi, i watch films with family on an outside movie screen atattched to the house so not far. I know my sky signal is rubish for where i live for now, i have to use my hotspot out side so the signal dosnt get lost from WFI

but.. on one movie night alone i ran out if data 3 times so rolled over 15gb of data for one movie. This has never taken data like this on other movie nights where i have watched two movies. Dose anyone no why this would happen?? 

[PandJ2020]

What phone do you have as most 'Hotspots' only use cellular data and will not bridge to WiFi.