Ok, so I'm probably the last person to discover this, but just in case...
Say you see a file you'd like to have, but it's been uploaded to a file host where you don't have an account.
Sure, you could use the free download at that host, but it will likely be much slower than the host where you do have an account.
I've noticed that if I do a search for the video title, I can usually find another thread on the forum where the same file has been uploaded to the file host I use.
Should I copyright this amazing invention of mine???