What do they mean?
 

when watchin a person on video taking a flash of someone and they said they metered for the sky in the background first, What have they done or how do they do it ?and what does it mean?

Difficult to say without seeing the video...

I presume they're taking a photo with the camera set to expose the sky correctly. You have to assume that this would underexpose the model so they use fill flash to light them.

These will help you:

[url]http://strobist.blogspot.com/2007/09/lighting-102-balancing-light-twilight.html[/url]
[url]http://strobist.blogspot.com/2007/09/lighting-102-33-balancing-flashambient.html[/url]

[QUOTE=ap4a;18531]These will help you:

[url]http://strobist.blogspot.com/2007/09/lighting-102-balancing-light-twilight.html[/url]
[url]http://strobist.blogspot.com/2007/09/lighting-102-33-balancing-flashambient.html[/url][/QUOTE]

Thanks , this looks just what I need, now its just a case of me trying to understand it, but if I do I will understand lighting much better , thanks alot