AF reduced to dust (here L-39) :

USMC :

You’re right. The video shows Entebbe in Uganda.
A purchase, albeit second hand, but does not make sense, since the machine has no military equipment more.

L-39ZO (Z for ZBRANE – weapons) is a interim weapon trainer variant for export.

And what about the civilian US registration?
Even from a purely legal it is but exclude an air force, outside the United States, civil certified aircraft flying with American registry.
On 11.5.2011 (date of the video), it was still a United States Machine.

Demo flight in Uganda with country roundels applied ? Seems that registration expired the 30/06/2011 in USA.

Romanian MiG-21 :

On the back of the helicopter are Albatrosses

Correct, good eyes.
Same air show :

Ugandan Mi-24PN (with limited thermal night vision):

Thunderbirds :