I remove the backdrops all the time and it only takes a few seconds for hundreds of files 
There’s plenty of programs that will do it … but my fav / simplest one is " textrep"
http://www.download25.com/install/free-text-blocks-replacer.html
a “2 step” procedure (follow the pics below exactly … change the path to your movies of course.)
click “Start” for Step1 … then “Start” again for Step 2 to complete the procedure.
P.S. Sure, you can theme edit to remove backdrops … but removing the backdrop tags from the xml’s has the benefit of faster navigation speed .
