is there any such web based flash torrent client available either free/commercial?
here is the main problem why there aren't any:
http://osflash.org/pipermail/osflash_osflash.org/2007-August/014099.html
as mentioned bellow: http://en.wikipedia.org/wiki/Comparison_of_BitTorrent_clients
you can see that there are no flash clients listed at all.
Its probably impossible because of security reasons: http://livedocs.adobe.com/flex/2/docs/wwhelp/wwhimpl/js/html/wwhelp.htm?href=00001950.html
How are other P2P applications, namely TinyChat, able to operate with Flash?
flashplayer can use p2p connections via udp but only on adobe stratus service which gives them unique keys every time they go online. then after one user passes his key to another (not using flash because they are still not connected) they can connect their players. chatroulette is the most famous example of adobe stratus p2p imho
and another problem: it's almoust impossible to write anything except text and pictures to a local machine, once i developed an swf that could pass music from my computer to a remote user, it was not so easy to bypass sound sending restrictions using ByteArray class and to re-generate the original sound on the back-end, but however i didn't find a way to save an mp3 file, the only idea was to launch a local web-server for saving, but than it would be rather stupid to use flash.
but if i had enough time i've tried myself at writing a torrent client on AIR xD