WRT the original Query .
Private Trackers, most of them use a PASSKEY system. Meaning.
X is a registered member of PrivateTracker P , so every torrent X downloads from P has a passkey ( generally a long string of encrypted characters ) inserted . Whenever X uses the torrent to download , the Tracker identifies the Torrent with X by checking the Passkey . Each member has Unique Passkey.
So even if ur friend sends u the torrent, if u download it its Ur Frnd's a/c which will be credited with Download Data ....coz the Tracker identifies the Passkey with ur frnds Passkey. And more importantly ...
all these Private trackers keep track of IP Addreses ... So if it happens that a torrent with same Passkey is being downloaded from different IPs ... chances r ur frnd will be banned! So make sure u verufy with him that there are no simultaneous downloads!
There is a second scheme too ..
Some Private Trackers Rightly claim that the passkey system puts Load on their Servers, so they use IP logging. meaning to download from that particual site, the member has to logon to the site. The Site records the Ip and allows dowloading only to that IP . So even if u hv ur frnds torrent u will not be able to download unless u can login to the a/c from ur PC coz ur PC will hv distinctly diff IP ... Demonoid Uses IP Logging .. but as they r not a private tracker they will not stop u from downloading even if u r not a member.
But if u want to Upload , and want to credit the Upload tab.. U will hv to login to demonoid a/c .. otherwise demonoid will not be able to identify the a/c with IP ...
Hope I was clear enuff to ur Original Query >>