LOL
This is funny I guess none of you ever had a lesson in networking?
Anyway, I'll make it short
With HTTP (the transfer protocol used to watch a webpage, but also for most filesharing networks) you don't have so-called Endgame. Endgame means that if you have 0.01% 'missing', you can ask that 0.01% from another source.
But HTTP cannot do it.
HTTP assigned that 0.01% to a specific source, but maybe it got offline, or it's using it upload for something else, anyway, it can't ask another source for that 0.01%, unless you delete/forget/disconnect from that specific source, so another source can give the remaining part to you.
Shareaza doesn't do this auto, because it's a very aggressive way to do, and will give faithful uploaders a lot of pressure on their pc.

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