Notacon provides a great deal of it's recorded content online for free and licensed under the Creative Commons Attribution-ShareAlike 2.0 license. This essentially means you can download and distribute the content for free, as long as you acknowledge that the content is owned by us and as long as you share your content freely as well.
The main distribution point for Notacon media is at the aptly named http://www.notaconmedia.com/.
Recordings are also distributed by BitTorrent protocol. To get all the files in a collection, just load the .torrent file in your client and let it run. To download some files but not the whole collection, make sure you're using a client that supports selective downloading, and deselect the files you don't want. (Refer to client documentation for specifics.)
2009 AVI video only: nac2009-video-final.torrent
2008 AVI video only: nac2008-video.torrent
2007 AVI video only (15 gig): nac2007-Video.torrent
2006 AVI and MP3 (16 gig): nac2006.torrent
2006 MP3 Only (150 meg): notacon-2006-mp3s.torrent