what I usually download are music "bootleg" files of a band that encourages and allows bootlegs both audio and video to be made at their concerts. They are not infringements on any publishing company.
Authorized Live-Taping Downloads - Etree.org
Another legitimate use of BitTorrent is by the Etree community, music fans that freely trade and distribute the music of bands that allow the audio taping of their live performances for non-commercial use. The Etree site lists over 100 bands or musicians who have policies that allow and encourage fans to tape and trade their performances, including major artists such as the Dave Matthews Band, Pearl Jam, Tenacious D and others2. Sanctioned distribution of live show tapes has been a tradition starting with the Grateful Dead, and many bands are realizing that having a loyal following is very valuable and that they can both support their fans and still sell records. Because the live taping community usually opts for lossless compression over lossy mp3 compression, the files involved are much larger than with normal music sharing. Because of this, BitTorrent is now the preferred solution for almost all of these legitimate music-sharing communities.
another use of BitTorrent would be when I have my own video/audio file to share .
http://news.zdnet.com/2100-9588_22-5778480.html
Internet browsers are beginning to provide support for Bittorrnet in the browser