No one said it was a white bird. Sun reflecting off of feathers can look white.
Sunlight interacting with the structure of a feather, rather than pigments within it, is what makes feathers appear white to us. The feather's microscopic structure scatters all colors of light equally, causing the feather to look white.
In essence, when the sun's rays hit these dark feathers just right, their intricate structure can reflect and refract the light in a way that creates a dazzling, sometimes seemingly white, effect, even though the underlying feathers are still dark- Google AI
Mr. Dunning-Kruger called people dumbass when he doesn't know shit.
In the context of aviation and meteorology, an updraft is a general term for any upward current of air, while a thermal specifically refers to a type of updraft caused by the uneven heating of the ground by the sun. - Google AI
A thermal is an updraft created by warming on the surface. While thermals are a type of updraft, updrafts are also caused by wind hitting a vertical surface, causing the wind to be deflected upwards. This is also called ridge lift.
Again, LEARN TO READ. I didn't say the bird flew behind the shadow of the trees. That's the voices in your head making up bullshit again... they have to work so hard to fill in the gaps left by your illiteracy. There could be a cloud, another ridge off camera to the right, or something else obstructing the sun.
Since your first video already demonstrates a clear shadow cast over the object, it's obviously a reasonable assumption that the same principle will apply to another bird.