I built a file with Notepad++.
It had the old filename a pipe new filename.
Import rename-pairs was under the Action tab, not under the File tab.
BRU would not take the file, although it's suffix was txt. BRU said it was invalid.
I checked Notepad++ and the file's encoding was ANSI.
I used Notepad++ to convert the file to UTF-16 BE BOM.
IT WORKED
Notepad++ had the option to convert to UTF-16 LE BOM. I did not try it.
It seems that Notepad created txt files in ANSI encoding. I do not know, the why.
After along day, I had a little knowledge of Notepad, very little knowledge of Regex, and finally found how to make the file compatible with Bulk Rename.
I now have 256 renamed MASH.mp4 files.
Thanks for the ability.