Need To Identify Two Programs,

I need help finding out about a couple of programs I have seen before that work with kazaa but didnt get them when I saw them and forgot where I saw them and what their name was.
The first allowed me to get a direct connection between two users on kazaa, to transfer files between the two. Or if there is another way to transfer a large file between two computers over the net, how the heck do I do it.
Also I need to find out how to fix a movie I downloaded. I have it on one machine and it works fine, but when I downloaded it to another, it is horrible. If I remember right there was a program that could go through a movie and find the corrupted parts and redownload just those parts of the movie instead of the whole thing.
Can anyone send me in a direction that I need to look to figure these two things out.
Thanks for your help in advance.