The camera is a sony action cam. The effect or trick was more of an accident.
The camera mount was moved to a different spot on the axle, the sticky padding was compromised possibly allowing camera to move from side to side with wind hitting the camera case.
Or, I think the camera can move a little inside the case allowing the side to side movement. (That may be what happened)
The sony action cam has built in anti shake feature.
I did not do anything special with the editing reguarding shake that I know of.
The software is IMOVIE on a mac mini. The camera is a Sony action cam HDR-AS15