HD-Corea has pretty much all of the girl pop performances, plus a fair amount of other artists and often complete music shows. It's all in HD though, so expect up to 10 gigs for a single show and most performances in the 150-300 meg range.
Here are the most recently upped files in the music category, to give you an example:
Sbs.Song.Festival.See.Ya.Toxic.071229.720P.HDTV.x264-GreenTea 116.06MB
2007-12-30.KBS.Song Festival.HD.720p.x264.-Myse 2.42GB
Epik.High.Fan.071230.KBS.Song.Festival.HDTV.720p.x264 112.10MB
2007 EBS Space Sympathy BEST2.720P.HDTV.MPEG2.AC3-JINs 1.46GB
KBS.Song.Festival.2007.720p.HDTV.x264-HDInc 2.90GB
wonder girls.to my boy friend(finkl).kbs popularsong festival.071230.hdtv.720p.x264.xpeed400 50.08MB
Peter.Frampton.show.me.the.way.ts.1080.samsung.demo.file 1.19GB
KBS.Song.Festival.Girl's.Generation.071230.KOR.HDTV.720p.x264-kkeng 1.15GB
20071230.KBS.Song.Festival.2nd.Music.Clip.1080i.MPEG2-heero 9.68GB
20071230.KBS.Song.Festival.EP2.HDTV.1080i.Mpeg2.Ac3-godworld 10.16GB
Girls'Generation-Hey,Mickey.071230.KBS.Song.Festival.HDTV.720p.x264.60f-jinuki 110.05MB
20071230.KBS.Song.Festival.1st.Music.Clip.1080i.MPEG2-heero 6.40GB
yoonha.password486.kbs popularsong festival.071230.hdtv.720p 100.13MB
KBS.Song.festival.071230.Girls`Generation-Girls`Generation.KOR.HDTV.x264.720p.60f-NotoriouS 146.45MB
20071230.KBS.Song.Festival.EP1.HDTV.1080i.Mpeg2.Ac3-godworld 8.49GB
2007.KBS.Song.Festival.1st.Girl's.Generation.1080i.MPEG2 910.57MB
And sorry, I haven't been a member long enough to have any invites, so you'll have to find someone else to let you in.
Oh, and the site + userbase are largely Korean, although they do have an English stylesheet so that the navigation is at least in English. All the posts, descriptions, and most of the rules/faqs/etc are still in Korean, but you'll at least be able to make your way around the site. And once you've used one tracker they're pretty much all the same...
Otherwise if you don't have the bandwidth/patience for an HD tracker like that, I'd recommend learning to use Clubbox. Personally I hate the program, but it is a simple way to get ahold of Korean media.