The yellow dots are aircraft.
It is a 24 hour observation of all of the large aircraft flights in the world, condensed down to about 2 minutes. From space we look like a bee hive of activity.
You can tell it is summer time in the north by the sun's footprint over the planet. You Can see that it didn't quite set in the extreme north and it didn't quite rise in the extreme south.
At the beginning of the clip watch all of the traffic from the US heading for Europe over night and then all of the traffic coming back to the US during the day.