I think it is humid and rainy in Kenya now. You don't know the conditions under which they were raised up till you got them.
I'm not trying to diagnose from afar, but if it was dactylariosis, when the fungus contaminates sawdust or tree bark used for bedding it takes about 6 days or so to...
Both caused by a fungus. It resembles in postmortem both aspergillosis and encephalomalacia.
Dactylariosis is caused by dactylaria gallopava. Aspergillosis is caused by aspergillus fumigatus. The symptoms are quite differernt though.
If it is dactylariosis, it is the fungus inhaled from moldy litter. Prevention is to replace litter and avoid mold. The treatment is as you did, cull affected birds.
It looks more like dactylariosis or congenital tremor. Both of which are rare but not as rare as Newcastle disease. Newcastle usually represents as droopy wings and slow leg movement. That's not what I see in the video.
Dactylariosis is caused by a fungus that affects the brain and lungs and...