The shutter speed was changed. You should notice that the exposure increased in the second clip, and the motion jitter and blur is due to a shutter speed that has fallen bellow the frame rate (below 25th/second).
If you shoot some video now as a quick test with a shutter speed that is below the frame rate, e.g one 25th of a second at 30fps, you will see it produces the same effect.
What might have happened is you might have accidentally switched the camera into an automatic mode on the touch screen or the dial without noticing.
If the shutter speed is not equal too or greater than the frame rate, the camera does not have enough exposure’s to produce all (25) frames for one second of video, and this results in the jitter.
I am 100 percent certain this is what is occurring in your video but if you are doubtful I would suggest testing it out yourself. There’s nothing you can do to fix this now unfortunately, however in the future make sure the shutter speed doesn’t change during filming as it has in this video evident in the miss matched frame rate to shutter speed as well as the change in exposure between shots.
Hope this doesn’t happen again! And I’m sure the video is more than adequate for reference purposes anyhow, but I’m sorry that this has happened.