By looking at the video, I completely understand your doubts in this and in order to determine what is happening it's important to know the context in which this went on.
When the symptoms started, was Ibi in a happy/playful mood, singing, head bobbing and showing definite signs of courtship? Did she regurgitate food towards her mate or directly onto a favourite toy or perch?
If not and this started out of the blue then Ibi has truly vomited.
Usually, when budgies vomit the motion they make with their heads is more out of control and the seeds scatter everywhere.
When you caught this on video, Ibi could have been at the end of the vomiting bout and that could be why the whole motion wasn't so intense.
How is she doing now? Is she behaving normally or is she a bit fluffed up and sleepy?
If Ibi has truly vomited and you notice a repetition of this, then booking her an appointment with the avian vet specialist would be the best thing to do.
I'm wishing Ibi and Bebito all the best.