That starling video was on Lough Derg on the River Shannon in Ireland. I used to live and birdwatch in that area for many years and saw some extraordinary sights. Apart from starlings, I would occasionally meet vast flocks of Golden Plover in winter - which can produce some of the same smoke-like effects. One of the tributaries of the Shannon - the Little Brosna River - held a huge flock of Blacktailed Godwits every winter; I remember being down by the river early one spring, with the flood plain still inundated and finding several small islands (say a few acres each in size) simply black with birds gathering before heading off north en masse . Beautiful.

One of the great joys of birdwatching is that mix of individual and mass treats, so to speak.

Regards