no -- they are post-production and hence to not 
add value to cels.  (though they do make them 
look nice).  

from what i gather, a laser copy background is 
just that -- a photocopy of the original 
background, often made when a cel sequence is 
split and sold (as only one cel in the sequence 
can be sold with the original, obviously.)

screencap backgrounds are typically made by 
collectors, from a screen cap of the frame their 
cel appears in (or a similar frame).  given that 
screencap quality is often poor, i wouldn't 
bother to print one out, though i've got a cel 
now that i display digitally against such a 
background.  (well, it was a scan of the original 
background, but it's about the same end result.)