Can't seem to get custom formula #2 "FindHandleName()" (that retrieves the handle name from the URL that's retrieved by custom formula #1 "getRedirect()") to populate as per normal. Might be an issue with the URL that's input in column B(?).

Sample sheet to test -

NOTES:

After a few runs, the server returned an Error 404 Request failed due to some videos that were deleted. I'd trust that error handling for that instance is a different question to be addressed, but this should get you started.