Okay so you've got the ISO on your desktop - good. In Windows 7, there is no native feature to mount an ISO like there is in Windows 8, which is why you have to watch the video. At approximately 21:30 it shows how to mount an ISO using 7-Zip, which is a free 3rd-party compression utility.
Originally Posted by joodyanne
So, download 7-Zip and install it.
Go to the ISO which you have copied on to your desktop.
Right-click the ISO and do exactly as in the video:
Starting about 21:30 in the video
Open 7-Zip7-Zip will then extract all the files within the ISO to your desktop.
Navigate to the ISO on the Desktop
Right-click and select 7-Zip>Extract Here
Once complete, close 7-Zip.Be prepared, as it will take a while.
Find the file on your desktop named setup.exe
Double-click it and your upgrade will begin.
If you want to read the tutorial on how to extract files from an ISO in Windows 7, see this:
ISO - Disk Image File : Extract to the Desktop in Windows 7
ISO - Disk Image File : Extract to the Desktop - Windows 7 Help Forums
Please just be sure you have all your important data backed up, just in case something happens. Usually, if there is a problem with the upgrade and it can't be completed, Windows will roll you back to your Windows 7 installation. But, every once and a while, some people have had problems with the rollback, so it's best to be safe and back up your data before upgrading.
Good luck. Really, it's not so bad.