I'm assuming your video shows "I open/go to a folder, close it, then straight away try to reopen it and sometimes it doesn't work?" (It all went a bit quickly for me!)
plist files don't update instantly -- preferences, including the Finder prefs you are pulling "last folder" from, are cached and then written to disk a little while later. You can see this in action by taking the AppleScript in you action into Script Editor, adding the line return itemNames immediately after the "System Events" tell-block ends, and running the script to get a list of recent folders. Open a folder that isn't on the list and immediately run the script and you'll see the list of names doesn't change -- if you repeatedly run (Cmd-R) you'll see the new folder name added after a few seconds.
If your problem is something else, try describing it here so we can read it while watching the video.
You got it. Should have held back with the hot keys though, things happen at light speed on my mac or nothing!
This makes a lot of sense. As the behavior seem in fact to show some kind of delay rather than failure. I haven't wrote the script. So, can't comment on the ins and outs of it. I am surprised such a simple feature is not built-in neither in Finder nor in Default Folder X...