Well, its short for InterPlanetary File System becouse it would be a sensible way of how you could share files on the internet such as the videos via Dtube even with lets say a mars colony (assuming there are some people with IPFS nodes on Mars). I dont have a big upload rate to mars (well, none at the moment but in a situation in which we would), so if 5 people on mars (simutaniously or not) accessed a file i have, nodes local to Mars would get it and distribute it quicker.

The same principle applies on earth, the storage and upload rate of one system are not infinate (but, vice versa, often not fully used) and even on those comparativly small distances, if you are in australia and want a file, it will still be more efficient to get it from a node in sydney rather than new york.