BestShare make clients in queue with very unbalanced U:D difference to gain score at bit faster.
Clients are sorted by U:D difference, and the best client is then granted an accumulating time bonus for the period it remains as the client with the best U:D difference (that is, it has uploaded us more than we have). Only the best client for each calculated period will have the bonus. The bonus, visible in the queue list near the waiting time, is kept by the client even after a new client is chosen as best. The bonus is added at the "regular" waited time. Once the upload slot is granted the bonus is lost (independently of the amount of transferred data).
 More details
Clients ranked as 5 and up to 1, once they are sorted by score, do not accumulate any bonus (they are already going to get an upload slot quite soon). However if they got a bonus earlier, it is kept and used for final score calculation. Best client is thus chosen from clients that are ranked by score from 6 and below. Time bonus is not saved, but has validity only during the current session. Bonus is kept if a client disconnects and reconnects later (but of course it won't increase during the disconnection period). Clients recognized as bad ones won't get any bonus. Yes, FastWeb clients will have the bonus as well if they have uploaded more than they have downloaded (which should be the usual case to get the time bonus for every client).
Final: This feature is experimental and introduced in ZZUL BastarD Mod 1.9.1 . It may (and probably will be) fine tuned in future. Any suggestion to improve it is accepted.