Question: how much video is 15 gb?
Answer: Going by what Netflix says the usage is, it is then simple division. The 15 GB is 15 with 9 zeros and 300 MB is 300 with 6 zeros. 15,000,000,000 divided by 300,000,000 (300 MB/hour) equals about 50 hours at low definition. At standard definition (700 MB/hour) it would be about 21 hours of viewing.