A lot of errors and problems with the World Editor, which are easier to show in the video than to describe.
Link to video #1 (3:24) → youtu.be/4nqJHJ-DxIQ
Link to video #2 (0:26) → youtu.be/zFQmBaWw4dg
Link to video #3 (0:39) → youtu.be/IkhASBYXm1o
Link to video #4 (0:25) → youtu.be/9DFCvM7j2Ww
Link to video #5 (3:19) → youtu.be/NFHwBXObuL4
Link to video #6 (0:54) → youtu.be/xotxffkor20