In fact I have seen some very complex scenes having ~100 objects, all animating independently (in what looked like proper physics) around creating great visual spectacle!
I am a newbie to vector graphics (using InkScape) and amused by how such nice animations are done.
Are they -
Done in some movie creating software ?
By hand (frame-by-frame) in Vector Graphics editing software ? (Looks really time consuming)
Something else ?
or my understanding is wrong and they infact are not vector graphics itself ?
Possibly the first demo (the cat) is a very good candidate for such things. However, its probably done in a animation software.
Most probably in some animation software. Such as After Effects, Adobe Animate, Flash, Toonboom Harmony etc. Even most 3d animation software would work well (I could make the cat in Maya in about 10-15 minutes, including tooling up, much faster in Harmony).
Animation is always time consuming no matter what you do. Software helps, but animation has a horribly high learning curve. Even animating by hand is not as time-consuming as you think, in context of animation always being time consuming.
So for example the cat could be made by hand quite quickly Id say about less than 20 minutes (It is a simpler animation than the rotation but not much). All you need to do is resign the nagging idea that there might be a better way.
Something else? What would that something else be, stop motion animation?