While it may be obvious to some, as a practical matter, steel doors should be considered a serious navigational hazard to indoor autonomous micro air vehicles due to the effects of the magnetic fields. This problem is especially noticeable in hallways with several closely spaced steel doors.
The effects for these fields on the pose estimate should be considered when calculating the magnetometer's sensor error model for the Extended Kalman filter. Otherwise the sensor will have a noticeable negative influence on the EKF output.
One of the symptoms of this problem that you may experience is that the fused IMU yaw data is less accurate than the unfiltered yaw gyro data.
The door shown in the video is not located near any high current electrical wiring and multiple, but not all, steel doors in several locations exhibited this behavior.