(NOTE: This issue appears to have been resolved as of Black Ops Patch 1.06)
How To Get Call of Duty: Black Ops to display Video Output:
If you're like me, you might have run into some (read: many) problems with Call of Duty: Black Ops on the PS3 Slim. I bought the game, brought it home and popped it in only to find than upon doing so - no image was displayed. Thinking I just had a bad disc, I exchanged for a new one. Still the same problem occured.
I've never figured out if this problem was unique to my television (A Panasonic Viera Plasma 42" 1080p), or my PS3 (Slim 120GB connected by HDMI) - but after numerous emails with Activision Technical Support (who, despite some of the horrible things I read about online, were actually very courteous and prompt in replying), I came up with a solution.
1. Scroll to Settings in the XMB (a.k.a the PS3 menu), and scroll down to Display Settings. Click this, and then choose Video Output Settings.
2. Choose HDMI (if applicable), then choose Custom.
3. Untick 1080p and 1080i boxes, leaving 480p and 720p ticked.
This worked for me right away. Obviously this is a temporary solution; requiring a manual change if one wishes to view 1080p content using the PS3 (Note: the native resolution of most PS3 games is 720p, even if they display at 1080p).. Hopefully Activision will address this issue in the next patch. Well, that and the horrific "Connection Interrupted" problems that keep robbing me of credit for 25+ kill team deathmatches...