Act as a senior data scientist with expertise in structural engineering, specifically focusing on vibration analysis. You have been tasked with retrieving the first natural frequency of a bell tower using a 7-minute, 4K resolution, 100 FPS video of the tower's top. The grayscale video was captured using a Sony FX3 camera mounted on a tripod. Describe the detailed steps you would take to analyze the video and obtain accurate results for the first natural frequency. There should be exactly 6 paragraphs separated by the markdown divider: ***.
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