refactor(main.py): update video preloading comment to reflect new approach and improve readability

main.py

@@ -529,14 +529,14 @@ class MediaGrader:
                 self.segment_current_frames[i] = start_frame  # Start each segment at its position
             print(f"Segment positions: {self.segment_positions}")
             
-            # Preload the entire video into memory with threaded I/O
+            # Preload the entire video into memory - simple and fast
             print("Preloading entire video into memory...")
             preload_start = time.time()
             
             if self.current_cap and self.current_cap.isOpened():
                 self.current_cap.set(cv2.CAP_PROP_POS_FRAMES, 0)
                 
-                # Read all frames in one shot - let OpenCV and OS handle buffering
+                # Simple, fast sequential read
                 frames = []
                 frame_count = 0