Case 1 : If cropping region is out of bound of the video, and Preview is selected the program will crash Case 2 : If preview is running and left/right/up/down arrow is pressed to move frames program crashes  
Case 1 : If cropping region is out of bound of the video, and Preview is selected the program will crash
Case 2 : If preview is running and left/right/up/down arrow is pressed to move frames program crashes