I’ve had the problem with my 2007 Macbook described here in the video, to the point where the screen didn’t light up at all. The customer service guy at the Apple store said I probably needed a new LCD lamp when in fact it’s just the inverter cable. The stores don’t carry the parts for such an old model (understandably), but powerbookmedic.com had everything I needed.
I took it apart as per the video, exposing the inverter cable, and the screen lights up fine now. If I hinge the screen it goes off but I’m able to tinker around with the cable to make it normal. I didn’t actually have to replace the cable at all.
Seems to be a common problem with older model Apple laptops. I’d follow the steps in the video if you see it happening to you. It might save you some repair or replacement money.