I noticed in your video that you left the bootable USB drives as MBR (Master Boot Record). I noticed the same thing when I reformatted my new thumb drive with Mac OSX Extended (Journaled). I understand leaving MBR if you were using a FAT partition, but is there a problem leaving MBR partitioning when booting a Mac formatted USB? Does GUID Partition Table have any benefits?
Partition map for bootable drives - Episode 4 - Mac Management Basics
The main reason I do that is out of habit. Only EFI systems support booting from GPT partitioned drives. If you stick with MBR then you can boot from EFI and non-EFI systems. So that is why I generally stick with it. If your system supports EFI (like most modern Macs do) then you can go GPT without worries. Either way, there is not a lot of benefit to using GPT on a USB device. You won't likely be able to use any of the SecureBoot features and very few people exceed the partition limit imposed on MBR devices. The exception would be if you had a USB drive over 2TB in size and you wanted a single partition.
Hope that helps,