Hardcore links on YouTube:

Avengers - "The American in Me" - live in 1978
http://www.youtube.com/watch?v=Eo2Ryh8dLbc

Babes in Toyland - video for "He's My Thing"
http://youtube.com/watch?v=QSf29cdGdJg

Bad Brains - "Attitude" live in 1979
http://youtube.com/watch?v=aWWI2rGdda4

Bad Brains - "FVK", "Big Take Over" and more - great 1985 Target Video stuff.
http://youtube.com/watch?v=XNVwBR8e9rs

Béruriers Noirs - "Porcherie" - French punk from 1985
http://youtube.com/watch?v=s8qnEbRsgx4

Bikini Kill - Interview and some live footage
http://youtube.com/watch?v=ZXq3YA9dTgQ

Biophobia - "Klon" (very aggressive metallic Venezuelan Hard-Core)
http://youtube.com/watch?v=TeeRbvb51-A

Black Flag - "Revenge" from "The Decline of Western Civilization"
http://youtube.com/watch?v=f5mjoN0SKoc

Black Flag - "Six Pack" live in 1981
http://youtube.com/watch?v=ju4DBK_71JQ

Charles Bronson:
http://youtube.com/watch?v=FN_M-8X353o

Circle Jerks - "Red Tape" from "The Decline of Western Civilization"
http://youtube.com/watch?v=iExJ2Jtlnlo

Circle Jerks - Target Video material from 1985
http://youtube.com/watch?v=OcR8Q9brRP0

Conflict - "From Protest to Resistance" Live British Anarchist hardcore
http://youtube.com/watch?v=U4BYF3kxWhc

Converge - 2 live tracks
http://youtube.com/watch?v=TGBoH-7rOUk

Crass - "Christ The Movie" (Parts 1-3)
http://youtube.com/watch?v=uymQ07fWgTk
http://youtube.com/watch?v=T2zC9VGfoag
http://youtube.com/watch?v=NTR-erGrICU

Crime - live at San Quentin in 1978
http://youtube.com/watch?v=JUxJSrlwZTQ

Crucifix - Live 1984
http://youtube.com/watch?v=5D_2SNA4n-c

Daughters:
http://youtube.com/watch?v=vKMgMG2orv4

Dead Boys - "Sonic Reducer" and some interview footage
http://youtube.com/watch?v=ZUEqbEzXOCA

Dead Kennedys doing "Police Truck"
http://youtube.com/watch?v=ZENFvsEqVEc

Dead Kennedys - "Bleed For Me" live in Los Angeles
http://www.youtube.com/watch?v=MfSoYJ0cD8Q

Discharge - "State Violence State Control" live 1983
http://youtube.com/watch?v=1y8Ay93XLl0

D.R.I. - "Suit and Tie Guy" - from 1988, as old as we can find so far
http://youtube.com/watch?v=mid1LPj4Y9M

Dwarves - "Drugstore"
http://www.youtube.com/watch?v=T15k0I2nOfk

Especimen - Antes de Morir
http://youtube.com/watch?v=SjzQYRj85cM

Extreme Noise Terror with The KLF at the Brit Awards in 1992. A legendary prank. This performance triggered a national furor after the one of the vocalists aimed a machine gun at the audience and fired off a load of blanks. You can see this at the very end before they drop the curtain on the band.
http://youtube.com/watch?v=o5cSUhAEjCA

Eyehategod - "Jackass in the Will of God"
http://youtube.com/watch?v=nCPv8ZLTNtQ

Faith - "You're X'd" from the Wilson Center, June 25, 1982
http://youtube.com/watch?v=NTPeRmMXxIM

Faith No More - performing in grindcore mode and terrorizing an MTV host
http://youtube.com/watch?v=Qd0tUrpSLZM

Flipper - "Way of the World"
http://youtube.com/watch?v=w4WK6xbXH0o

Fugazi - "Waiting Room", 12-29-1988, Wilson Center, Washington D.C.
http://youtube.com/watch?v=KGTZGG2c160

Gauze - Several songs by these Japanese Hardcore maniacs
http://youtube.com/watch?v=snEn8PZkotg

Germs - live at the Whiskey.
http://youtube.com/watch?v=bzm2cNQQ6mE

GISM Sakevi vs. Jagatara
http://www.youtube.com/watch?v=eGvPky_ggcE&search=G.I.S.M.

Gorilla Biscuits - reunion at CBGB's - their entire set:
http://youtube.com/watch?v=VD95B1WqyaA

Iconoclast - video for "Battlefield" by this Southern California Anarchist band
http://youtube.com/watch?v=5V2nSWiRxTk

Infest - live at 924 Gilman Street in1989
http://youtube.com/watch?v=d4WtwdtrgvE

Kraut - 2001 reunion show at CBGBs
http://youtube.com/watch?v=P8wpt7dNHJ4

Limp Wrist - Live at The Smell. Great footage that came with a Discography CD
http://youtube.com/watch?v=ICf2uk7RZAM

Lip Cream - more furious Japanese hardcore!
http://youtube.com/watch?v=1FnEEMIYAGk

Lip Cream - even more! 12+ minutes of live stuff
http://youtube.com/watch?v=unOkZp0j0iY

Melt Banana - Live in 2000 at the Fireside Bowl in Chicago
http://youtube.com/watch?v=5LoS0_lHuSQ

Minutemen - "Political Song For Michael Jackson To Sing"
http://youtube.com/watch?v=Uab-BFYTApw

The Misfits - "We Are 138"
http://youtube.com/watch?v=2myo8LvbpyA

The Misfits with John Brannon doing songs by Negative Appraoch and Black Flag - horrible quality but as a piece of history this is pretty special.
http://youtube.com/watch?v=16xDAyigg00

Naked City - John Zorn and Co.'s Jazz and Hardcore merger:
http://youtube.com/watch?v=11cXP_tOZWY

Napalm Death - "Scum" - very early live footage from the first LP grind-core days.
http://youtube.com/watch?v=VzmXQY0l5Xs

Nausea - 1980's New York band's video for "Cyber God"
http://youtube.com/watch?v=3_U6ORbDC9Q

Negative Approach - Several songs live in 1983.
http://youtube.com/watch?v=NFsAvzRLYW8

Oblivians - "No Reason To Live" live at Emo's
http://youtube.com/watch?v=ZFIHqLwhnTw

Oi Polloi - "Tony Blair Fuck You" ("He's a fucking tosser!")
http://youtube.com/watch?v=6vvJKXnBB6Q

Outo - live in Japan 1989. Another one of the great Japanese bands totally destroying.
http://youtube.com/watch?v=CogF7Pyno3U

Pagans - "Dead End America"
http://youtube.com/watch?v=vrJ-u47KibE

Pekinska Patka - "Ja Sam Panker u Sakou Starom" Raw old punk from Yugoslavia!
http://youtube.com/watch?v=46c9cVg2QPw

Ratos de Porao - live on Brazilian TV on what appears to be a teen variety show
http://youtube.com/watch?v=QIf2iBu7_3Q

Reagan Youth - "USA" Live @ Tompkins Square Park '88
http://youtube.com/watch?v=0okU83_rHNE

Recharge - live German hardcore
http://youtube.com/watch?v=d16HJ5k3E7w

Rich Kids on LSD - "It's a Beautiful Feeling"
http://youtube.com/watch?v=NX02GVOpt18

Siekiera - Live in Poland 1984
http://youtube.com/watch?v=70EGicQq1Z8

S.O.A. - "Draw Blank" live at D.C. Space in 1980. Yep, that's baby Henry Rollins singing.
http://youtube.com/watch?v=YiKeBphycVI

Screamers - "22 Hours of Fear"
http://youtube.com/watch?v=B-Bw3pf9RpY

SSD - "Get it Away"
http://youtube.com/watch?v=fDvh0i9-YIY

The Stalin - three great clips by this old Japanese punk band with a thoroughly wild singer. The third video, taken from Japanese MTV is fully unhinged and downright frightening.
http://youtube.com/watch?v=UtvSefv45oE
http://youtube.com/watch?v=fT0QoYH-d8Q
http://youtube.com/watch?v=vUzjlYSuFNA

Teen Idles - "Deadhead" live on Halloween, 1980 in D.C.
http://youtube.com/watch?v=CyR9X622lQI

Teengenerate - "Wild Weekend"
http://youtube.com/watch?v=NO-OZ6XB4xk

Urban Waste - live at CBGB's in 1983 - 15 minutes!
http://youtube.com/watch?v=2cpXPtxNZ8s

Void - Live at the Wilson Center in D.C.
http://youtube.com/watch?v=ad49_a54e_A

X - live on... David Letterman?!? Maybe not their best but...
http://youtube.com/watch?v=7O0-wpKIA7o

Youth of Today - video for "No More" - meat heads vs. meat eaters
http://youtube.com/watch?v=78B0f4GvJ2Q