In order to get the desired effect you must set key frames in the motion section of the effect controls.
Heres a quick step by step for ya
-> Go to Effect controls
-> Open Motion
-> Set your timeline to when you want the vidoe to start shaking
-> Click the little stopwatch to start setting key frames
1. -> Move the video slightly in any direction
2. -> Move the timeline 1 or 2 frames (depending on how chaotic you want the)
3. -> Now there will be a small diamond to the right, click it to set a keyframe
-> repeat steps 1 - 3 for the desired amount
Hope that helps if you need more help feel free to ask
(Im an editor so i can help with any other questions you may have)