I have a MacBook Pro and a MyStudio WD hard drive. I backed everything up to MyStudio and would like to play movies from there (as to delete a free up internal hard disk space). Is this possible?
Well, how did you backup your files?
If you used Time Machine your files are backed up into a sparse image bundle which is built out of hundreds of 8MB bands (files). Playing back a file from this possible but may result in stuttering although possible.
If you backed up your files via drag and drop there shouldn't be any problem playing them. After all external hard drives are meant for the purpose of storing files and using them later on.