"I think they were lucky that this happened over water"
Nay.
The skids bending absorb most of the G's on a vertical descent quite well. An inpact to water from the same altitude and level attitude has More G's on the occupants, not less.
Regarding the camera frame rate. I'm sure the video is compressed to be put online, likely lowering the frame rate. I'm not sure assuming 30FPS is reliable.