Q: Lost iTunes extras button after moving movie file

I recently purchased a movie in Tunes Store which came with several features in iTunes Extras, including an extended version of the movie. To save space, I moved the movie file out of my computer to an external HDD, so I removed it from iTunes and added it back to my iTunes library from the new location. The movie plays just fine, but only the regular version of the movie, since the iTunes Extras blue button no longer shows up and I can't access any of the additional features, including the extended version, which was one of the reasons for purchasing the movie in the first place.

Any idea on how to solve this? How is that simply moving a file removes all the iTunes Extras functionality?