Didn't watch the video, but they'll be on cleansing flights, they're doing spring cleaning, bringing out their dead, scrubbing it all clean! Stretching their legs, etc.
Sure is good to see!!
The worst part is if they haven't flown for a while...they'll poop all over you. Smells horrible, last year I had to change my shirt several times a day :-D.
You should be seeing pollen soon, if the weather holds, the crocuses, willows, and maples are almost blooming.
Rick