I need help creating similar camera motion shown in the video

I would start by moving the anchor point further back, not in the actual center of the scene. This is a common mistake when working with 3D layers and the short distance between the center of view and the actual camera origin alone makes things look bumpy due to the angle calculations being weird. Other than that you definitely need a third keyframe on the camera and need to adjust the tangents to get a nice arching motion. I also would not blindly just set the keyframes to ease. This rarely ever works for camera motion, either.

Mylenium

Without actually seeing your timeline with the keyframes and the graph editor curves we can't realyl tell you much on where things may go wrong, but as Rick already pointed out these things simply take practice to understand how to tweak keyframes and how to create smooth motion with as few keys as possible. Judging from your sample video it feels like you haven't quite figured out AE's separation between temporal and spatial interpolation and thus the start of the motion looks very bumpy because the speed isn't credibly matching with the actual distance covered. Either way, the aforementioned screenshots would be the only way for us to realyl understand what you are doing.

Mylenium

Moving the camera takes practice. Control the motion path by using 4 Views. If you have All Keyframes selected in Preferences/Display and use the pen tool, you can curve a motion path and add additional arcs. The fewer keyframes you have, the smoother the motion will be.