Which has a free trial version: https://chrome.google.com/webstore/detail/jstorrent-lite/abm...

The paid version of Vuze also allows streaming torrent videos http://www.vuze.com/features/playnow

So all in all, hardly a new concept, but this looks really convenient to use.

Tribler is free and will prioritize piece-picking to allow immediate playback while the download is in progress. This has long been frowned upon in the BitTorrent community and usually leads to client bans from the more pickiest of the private sharing sites.

http://www.tribler.org/