I am NOOOOOT a budgie expert (although I have "owned" one)..To me, in this context, it looks like possible regurgitation or courting/mating behavior. DO NOT QUOTE ME, AS THAT IS A GUESSSSS!!!!
I hope others will chime in.
It really does seem like is is wanting to..."feed" your other bird...which is very sexual for adults, so keep that in mind and 500% remove any shadowy spaces etc.