James at 2011-05-11 16:40:50:
I think an important thing to point out, is that residuals exist in place of royalties.
Royalties are a percentage of profit from work you own or created. Since studios typically buy scripts and claim full ownership (and authorship -- which is primarily a very American interpretation of copyright) the writer's guild set up Residuals as a replacement.
In theory, they are the same thing, but avoid a semantic technicality that producers were able to easily exploit.
The irony is the harder studios squeeze writers to limit back end participation and lower residual payment, the more incentive writers have to fight for authorship -- which potentially cuts out a much larger chunk before even proving successful or not.
Hollywood business practice is not only greedy, but self destructive.