1) Root Explorer is a paid app, thus you can not post a link to it. Please refer to the rules and guidelines involving Warez.
There are free apps that can do the same thing, such as ES File Explorer.
2) Not all devices have their boot animations in /system/media. Some are in /system/customize/resource or /data/local and maybe a couple other variations. And many Samsung devices that do not have custom roms installed can't use bootanimation.zips because they have a special format called qmg and have a slightly different set up.
Need some help, advice, something fixed? Hit me up on Hangouts @ es0tericcha0s and check out my site: http://mobilemojo5280.com
for more info!
HTC Droid Eris / Motorola Droid / Samsung Galaxy S Fascinate / Motorola Droid X / LG G2x / HTC Evo 3D (x2) / Samsung Epic 4G Touch (Sprint S2) / HTC Amaze / Samsung Galaxy S3 (International) / Samsung Galaxy Note 2 / Nexus 4 / HTC One / Samsung Galaxy S4 / Sony Xperia ZL / Nexus 5 / ? (One+1 maybe...)