DJI Phantom 3 SE - Never crashed.
What can be the reason for this wavy video

Here is the example videoo, downloaded from SD card not from phone

An earthquake or more likely what Geebax explains here.

Check the following:

1) gimbal dampeners are mounted / fitted properly.

2) props are in good shape, not damaged or warped.

3) Calibrate IMU, calibrate gimbal

Hi, Poyazov. Thank you for raising up this concern in regards with the shaky gimbal on your aircraft. If this is the first time happened, you may try updating/refreshing the firmware of your aircraft: Then performed the gimbal calibration. If the same issue occurs, then I recommend you to send in the unit to our facility for a repair. You may submit the request online, just simply click on this link: https://repair.dji.com/repair/index