Set creation date and time in Meta data for MP4 files

I have several hundreds .mp4 video files that all appear erroneously at the same day in the photos app because they all have the wrong (means equal) creation date and time in their meta data. Luckily, the file creation date and time is still correct.

So what I am looking for is a short script that reads the creation date and time of the file and copies that into the Meta data. I assume an alternative would be to simply delete the creation date and time in the Meta data. In that case I expect the photos app to sort according to the file properties.

For the application of the script I would export all videos into a separate folder to run the script there and re-import them into the photos app after successful solution of my problem.

Thanks a lot in advance for any good idea.

Regards, Mariano

Model: iMac middle 2012, latest OS X
Browser: Safari 601.3.9
Operating System: Mac OS X (10.10)

set vidExts to {"mov", "mp4"}
set dir to (choose folder)
--set dir to "Mac HD:Users:drlulz:Desktop:test:" as alias

tell application "Finder" to set vids to every file of dir whose name extension is in vidExts

set theFiles to {}
repeat with i in vids
	set posix_path to POSIX path of (i as alias)
	set cmd to "GetFileInfo -d " & posix_path
	set datetime to (do shell script cmd)
	set datetime to explode(" ", datetime)
	set Date24 to item 1 of datetime
	set Time24 to item 2 of datetime
	set theDate to date (Date24)
	set time of theDate to Time24to12(Time24)
	tell application "Photos"
		set currentImport to import (i as alias)
		repeat with i from 1 to the count of currentImport
			set thisItem to item i of currentImport
			set date of thisItem to theDate
			--set date of thisItem to current date
		end repeat
	end tell
end repeat

on Time24to12(Time24)
	set theSplit to Time24 as text
	set text item delimiters to {":"}
	set H to text item 1 of theSplit
	set M to text item 2 of theSplit
	set S to text item 3 of theSplit
	set text item delimiters to ""
	return (H * 3600) + (M * 60) + (S)
end Time24to12

on explode(delimiter, input)
	local delimiter, input, ASTID
	set ASTID to AppleScript's text item delimiters
	set AppleScript's text item delimiters to delimiter
	set input to text items of input
	set AppleScript's text item delimiters to ASTID
	return input
end explode