At the bottom of the thank you page (http://valvearg.com/thankyou/), there are links to a bunch of contributors' steam profiles.  On each of these profiles, there is a bit of binary text.  That binary text is part of a link.  The binary is actually binary of a base64 string.  If you decode that base64, you get a bit of a link. 

Steam name   | binary                              | base64 | text
ChrisP       | 01100001 01001000 01010010 00110000 | aHR0   | htt
Dobz         | 01100011 01000100 01101111 01110110 | cDov   | p:/
Inriconus    | 01001100 00110011 01011010 01101000 | L3Zh   | /va
Jeth         | 01100010 01001000 01011010 01101100 | bHZl   | lve
Leveraged    | 01011001 01011000 01001010 01101110 | YXJn   | arg
MadJack      | 01001100 01101101 01001110 01110110 | LmNv   | .co
Rockin_Munki | 01100010 01010011 00111001 00110000 | bS90   | m/t
Sneeza       | 01100001 01000111 01000110 01110101 | aGFu   | han
stS          | 01100001 00110011 01101100 01110110 | a3lv   | kyo
Terrox       | 01100100 01010011 00111001 01110111 | dS9w   | u/p
Tinox        | 01100100 01010011 00111001 01110101 | dS9u   | u/n
Vicious      | 01011001 01111001 00111001 01101111 | Yy9o   | c/h
willwill     | 01011001 01111001 00111001 01101000 | Yy9h   | c/a
Xerdies      | 01100011 01101001 00111001 01101011 | ci9k   | r/d
Zemnmez      | 01100011 01111001 00111000 00111101 | cy8=   | s/

http://valvearg.com/thankyou/pu/nc/hc/ar/ds/

If you read the punch card in the video from left to right, starting at the top, you will get

0110100001110100011101
0001110000001110100010
1111001011110110001001
1010010111010000101110
0110110001111001001011
1101100111011010010101
0111001100110101010101
0101110000000000000000

which, separated into bytes and removing the leading zeroes (which is null, which is what strings are terminated by in C) is

01101000 01110100 01110100 01110000 00111010 00101111 00101111 01100010 01101001 01110100 00101110 01101100 01111001 00101111 01100111 01101001 01010111 00110011 01010101 01010111

which, translated from binary to ASCII is http://bit.ly/giW3UW which points to http://valvearg.com/thankyou/supersecret.ogg which is an SSTV image of http://tof.canardpc.com/view/6892b0ae-c760-45cb-93a4-115a66e8ad3d.jpg