This operation used a 'Frame Rate: Same as original' strategy which preservered the 'playback' frame rate of the various secondary control defined segments creating a file with a total average recoded frame rate of 43.65 fps-a frame rate below the critical threshold required for the QT X player to now display the secondary control. At some point in your workflow the original file (with the secondary slow-motion slide control) was saved (read as 'exported') with the normal motion and slow motion segments set to the positions as they are currently rendered during playback. This is a quick test that should easily identify and confirm which files have been 'modified' somehow on your system. On the other hand: In the case of my own 720p120 sample file, QT 7 Inspector window indicates the file's actual recorded 119.88 fps frame rate while the QT X Inspector window reflects the current 'effective playback' frame rate of 40.87 fps as currently defined by the QT X secondary motion speed slide control. To demonstrate the change on your computer, simply open and compare the frame rates of an original and 're-saved' file in both the QT X and QT 7 (or similar) media player apps: In the case of your sample file, both QT 7 and QT X players reflect the same 43.65 fps frame rate meaning that the effective playback and recorded frame rates have the same value. Unfortunately, your workflow as explained above, re-stores the 'effective playback' frame rate as the permanent total average frame rate-basically locking in the 'effective playback' frame rate as the 'recorded' frame rate for the file. And, even though the QT X 'Inspector' window reflects the 'effective playback' frame rate as the combined total average frame rates of your 'normal' motion and 'slow' motion segments, the actual 'recorded' frame rate of the original file remains unchanged. MORE BACKGROUND: While your original files have a recording frame rate on the order of 240 fps, the QT X player achieves the slow motion effect by 'playing' all or a portion of your 240 fps file back at a much slower rate as defined by this secondary slide control.