Welcome to Tom's Hardware, Sandra!
I'd suggest you ask your brother what is the file system of his external WD Elements. It's possible that your TV is not supporting NTFS-formatted devices, which would explain why your WD Elements is not being properly recognized there.
I'd recommend you backup your movies on the computer again and then
reformat the WD Elements using the FAT32 file system. Once you have done this, copy back your movies to the external and attempt to plug it to the TV. Hopefully, this time it will be properly detected.
However, there are
some limitations when using this FAT32 file system, you should be aware of. For example, you won't be able to transfer files larger than 4 GB.
Keep me posted if you encounter any issues, though. Good luck!
SuperSoph_WD