One of the elements from the Harry Potter book series that you can incorporate in your kid's party is the moving paintings bit. Of course, one does not always have the means to rent/pay for a digital signage at your child's party but there is another technology you can utilize.
Rent, borrow or buy your own digital photo frames. Just consolidate all the pictures (or edited images) you want to showcase and save it in an SD card and plug the digital frame for all to enjoy. Cheaper and quality versions are cropping up everywhere. Now, you also need not be bothered by finding or renting a whole screen just to play all the pictures you took of your baby (and trust me, not all guests want to be bombarded by such big pictures the entire time the party's ongoing).
Plus, these digital frames can spice up a dessert bar or buffet without being too visible as to take away from the main elements. Enjoy!