I've moved videos to a new drive outside of MC.
There is your problem. You should have used the MC RM&CF function to move the files, then all would have been good.
Then you tried to use the RM&CF function to
rename the files, instead of using the "Update database to point to new location (no file rename, move, or copy)" option.
Reading for you:
https://wiki.jriver.com/index.php/Rename,_Move,_and_Copy_FilesGenerally speaking, don't move files outside MC, unless you are sure you know what you are doing. Lots of people do move files outside MC, but even if you use the "Update database to point to new location (no file rename, move, or copy)" option afterwards, things can go wrong if Auto Import is running in the background and set to Fix Broken Links.
PS: Because the RM&CF function thought it was moving a file to a directory it saw already had a file of that name in it, MC correctly added the suffix to prevent the file in the target directory from being overwritten, which would be very, very bad in most situations.