Because while in the map editor, the map can be moved and zoomed very quickly with ALT and the mouse buttons / wheel, in the MT surprisingly one has to use the cursor keys to move the camera.

Please keep the basic mouse movement as it is in the editor also for the Media Tracker,
especially when the trigger block placement mode is active.
This would be very consequent and not confusing.
(note: I'm not new to MT editing, but this break of mouse usage philosphy always feels very odd, especially after longer map editing)