According to the wikipedia page for the Mr.Mr. EP, there was a data loss of some kind during the editing process where a large chunk of footage was lost or deleted, preventing the MV from being released when previously expected, and forcing a re-shoot of the lost footage. Insiders and SMent reps claim the company is working on data recovery also.
The original intended release date for the MV (music video) was Feb 19, a day before their intended M! Countdown comeback on Thursday Feb 20 — but the comeback has been pushed to Thursday March 6th, so hopefully March 5 might be the music video release date.
Do you have any more info? Please post in the comments!
Correction! It’s out now on Feb 28 :-3