The red filenames are from people behind firewalls, as I've understood it, the black ones are not.

The blue speeds are actual measured speed at the moment of measurement(it may vary), while the black speeds are what the users themselves have stated that they have.

Sometimes, the real bandwidth of a user may be totally different from what it says in black, for instance a guy which is stated to have 1000KB, may have so many people downloading from him, that by the time you come along, you only get a download speed of 2KB!

Where as the blue ones are "true" speed(at that moment).