Hi there and
to the forums!
Unfortunately, your video still did not upload properly.
However, I agree with Therm and Pretty boy that budgies tend to have a slight tail bob while resting, or also when they're chirping quietly to themselves. If this is all it is, there is nothing to worry about, whereas a more pronounced bob accompanied by a wheeze in breathing or lethargy should be looked at right away.
If you're unsure, I do agree completely that the best course of action is to take your little on to a qualified avian vet so they can help you to figure out the problem.
In the meantime, be sure to read through the budgie articles and "stickies" (posts stuck to the top of each subforum for easy reference) to ensure you're up to date on the very best budgie care and practices!
If you have any questions afterwards, please do ask as we'd love to help!
Hope to see you around and we'd love to meet your little budgie when you get a chance!