I'm pretty sure it is not birds or space junk, but rather, Scotch thistle seeds which blow in the wind at a great range of alititudes. They are also known as Santa clauses, which is quite topical this time of year
Look up near
the sun in rural NSW, and I daresay, much of inland E Australia, with telescope or binoculars and you can see dozens to hundreds of them drift past the sun each minute. They are a huge distraction when looking for Venus in daytime near the sun.
Forward scattering makes them bright at near-sun angles, relative to the background blue sky, (but dark against the face of the sun) but not so bright further away from the sun.
They are generally out of focus in the video, the larger they are, the more out of focus, since they are at lower altitudes. If it really was space junk they would be in focus, if it was birds, you would see their shape, rather than the round diffuse fuzzballs in the video.