Bootcamp help

Ideally, the drivers will be on the same USB drive as the Windows installation. That way the drivers get installed at the same time Windows is installed.
Go back to the video you watched but do not uncheck the option to "Create a Windows 7 install disc".
Leave all three options checked.
Let Bootcamp create the USB install disc and download the latest drivers.
As long as you use an 8GB USB everything will fit on the one drive.
Use USB 2.0 and not 3.0.
If you did use USB 3.0 then you can try booting back into OSx and recreating only the driver disk with a USB 2.0 drive and then go back to see if Windows can successfully read the drive. That could save you from starting from scratch.
If your drive is already USB 2.0 you could also try plugging it into a different port. That sometimes works also if you don't want to start from scratch.
And if you do start from scratch you'll need to erase your original Bootcamp partition before running Bootcamp because it won't create a new partition if it finds one exists already.
Don't go to the Bootcamp support site.
Don't download the drivers manually.
Just run Bootcamp assistant and let it do all the work.
It might take longer but you'll know that you're getting the right drivers for your specific hardware and you'll get an installation process that installs everything in the right order for success.