This is so important that it bears repeating: test, test, test.
Use multiple phones. Use both iOS and Android. Make sure your code is scannable before you print it out hundreds of times.
If you find that there is a mistake with the content of the code, (like, it links to the wrong video on your YouTube channel, for example), no problem! Just edit the content of the code. There’s no need to reprint it.
Customizing your code can bring more scans your way. Use colors, change the shape to suit your branding and add a gradient to catch people’s eye. QR codes give you the ability to let loose with your creativity, so go wild!