Yes you can follow that video tutorial if you think you need to. I can't say if it is correct or not because I have never used Windows 8, nor have I ever downgraded it. So if you find problems following the video I can't help you with that.
USB ports will still work with Windows 7,
but unlike Windows 8, Windows 7 does not natively support USB 3.0
So if your ports are USB 3.0, you need to install the
Windows 7 USB 3.0 driver for your laptop model from Toshiba's website.
If they don't have a USB 3.0 driver for Windows 7, your USB 3.0 ports will not work.
That's why it is so important to make sure that Toshiba have all the Windows 7 drivers for your laptop model before you go ahead with the downgrade..
For USB 2.0 ports you don't need to do anything, the driver is included in Windows 7.
Good luck!