My idea is add an new setting to automatically downloading First OR Last Piece, almost all clients have this setting (utorrent and others) but all download automatically but not in an inteligent way. My idea, add this setting with two lists, list 1 "Download First Piece" and list 2 "Download Last Piece". Because many containers put the header in the first piece, an some put in the last piece, so, with this lists, Tixati can priority only and just the "right piece" first OR last, for an specific media format, and tixati can serve both lists pre-configured with correct values for common media extensions. This way tixati can download automaticaly first "OR" last piece, not both together, just the needed for media preview.

It wouldn't "hurt the swarm", it would actually help it. That claim assumes that the torrent is desirable. If not, then by having a subset of the video downloaded prematurely, one could more quickly determine that the torrent is trash (fake files etc), and cancel the download before spreading it any further, thereby killing bad torrents.