Video file sizes

[GroundBreaker]

I've seen, when downloading episodes, some episode, with 1080p is like 1GB in file size, while in some other case, the same episode with 1080p resolution goes to 6GB, and some to nearly a 9! I dont understand how this works, but for a comparison I downloaded them both, and surprisingly both feel the same, and the audio too. What's the catch?

 

[rocktalkrock]

The more action, movement and image complexity in a movie, the larger the bit-rate needs to be. 7.1 audio will also take up more space than stereo and so a larger file.