How to smooth a time lapse video
In order to get a smoother timelapse you should shoot at a higher frequency. If you want you can always blend between two images results in somewhat more smoothenes.
The first video however is made with a totally different technique, there we only have a few videos and use morphing to get from one image to the next.

This technique interpolates the colours on one hand, but also the position of different points on the image on the other hand. This requires you to find some keypoints on both images in order to find a corresponding function. There are softwares that can do this for you, but I do not know any I could recommend.