Filming it is the right call. This way there can be no doubt as to what happened if someone is looking for the burger later, and they can get it comped by the restaurant without issue should they want another.
And with the whole table empty of people they had either already finished most of their meal/weren't that hungry, or it's a fake video.
Check your local library (if you're lucky enough to have one). Mine didn't have any rpg adventure books in stock but they let me search their online database and I found some that looked interesting. They shipped them in for me to borrow, at no cost to me. Amazing service!
It's a great way to try different adventure books before buying the ones that suit your style. Some adventures are quite fleshed out and some are bare bones with plot holes you can fill however you want.
Another thing that can help is to bounce ideas with other DMs or players that aren't in the campaign: give one a call if you know them irl, or make a post online, if you get stuck and need inspiration. Two heads together are greater than five heads alone, believe me.
Finally, take notes. Inspiration can come from the oddes sources, so write down anything and everything that might be usable at some point in the future: talk during the campaign, overhearing gossip about a stranger, books, movies, poems, games, dreams, working on a problem at work/school. Reading the notes back later can either be gibberish or lead to an idea to use.
Some cats are like this. I'd like to add a speech bubble to the last frame: "You may be leaking but I still trust you fully, I know you're safe and reliable. You always have my back, see?"