The amount of space taken up by a movie depends on various factors, such as the movie's length, resolution and encoding. Estimates of the space used by a movie vary between 1/3 of a gigabyte to upwards of 7 gigabytes.
According to TalkTalk Business, a rough estimate of space required to download the typical film is 700 megabytes to 1.5 gigabytes. Streaming an hour of video uses 250 to 500 megabytes of data.
Streaming video on an iPad uses up 2 gigabytes of data over six to 12 hours of streaming movies, correlating to 1/6 to 1/3 of a gigabyte used per hour of video.
The amount of data used to stream video is around 0.3 gigabytes per hour at low quality, 0.7 gigabytes per hour at medium quality, 3 gigabytes per hour at HD quality, and 7 gigabytes per hour at Ultra HD quality.