Let me put this into clear words with examples :

I find an entire MP3 album on someones client .
14 files in total .
My limit for downloading multiple files at once is 8 .

The guy with the songs has put his upload slots to 4 .

Now what happens when I start downloading that album ?

I get 4 downloads going , 4 other saying "waiting for 1 busy" and the remaining 6 are "queued" .

The other guy's upload slots are full .

(Mark 1) Now when the 4 files that were downloading are completed the other 4 waiting for "1 busy" immediatly jump on it and start downloading .

And the next 4 out of the queued list of 6 get into the "waiting for 1 busy" mode

Then we go back to the previous situation , now named "Mark 1" just to show you wich text part I mean .

This continues till al files are downloaded .
In that time no other user can get to that client since his upload slots are full and when one opens the immediatly fill up again .

While our first guy is downloading another user comes by and finds that he can't download because every transfer says : "waiting for 1 busy"

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Now what Mr. "unregistered" who started this trhead means is the following :

I find an entire MP3 album on someones client .
14 files in total .
My limit for downloading multiple files at once is 8 .
My limit for downloading multiple files at one from one host is 2 .

The guy with the songs has put his upload slots to 4 .

Now things go a little different whit that new limit .

I get 2 downloads going and the other 12 are queud .

The other guy's upload slots are : 2 full and 2 more open .

My 2 first downloads finish and the 2 next ones from the queued list start .
The other guy's upload slots stay the same .

While the the first guy is downloading songs 2 at a time another user comes by and wants to download too .
Now that users also has 2 upload slots he can use to download avaible to him .
He can start downloading too with 2 files at a time .

Now atleast 2 people can download files from that guy instead of one downloader tying it up completly and the second one waiting for the first one to finish .

Clear enough ?

Now when do we implement this one ?
Sounds like a winner idea !