Most of that video is about having Windows' bootloader (rather than GRUB)
start by default and propose an entry to start GRUB, which allows to boot
GNU/Linux... and Windows. I see little point in doing that: just install the
boot loader (GRUB) in the MBR (the default). It will start right after the
computer is switched on and display a menu (shown in the video at 12:25)
listing all the systems that are installed in your computer. Contrary to
Windows' boot loader, its automatic configuration should be OK. In
particular it auto-detects all installed systems.
Between 2:45 and 4:35 (the only relevant part), the video shows the use of
the partitioning tool integrated to the installer. In the video, one single
partition is used: the mandatory one, where to mount /. As I explained you,
I additionally recommend a separate partition where to mount /home (as large
as you can afford) and a swap partition (you apparently want 16 GB, which is
fine).
In the video, the user pre-created the partitions in Windows and formatted
them in NTFS. It is only a lost of time: he had better pre-created them in
GParted and directly formatted them the way he wants for his GNU/Linux
installation (Ext4 for / is fine; I recommend XFS for /home). In this way,
he would not have to "format the partition" during the installation process.
But you do not even have to to pre-create the partitions in GParted (or any
other tool): in the partitioning tool integrated in the installer, the "-"
button deletes a partition and the "+" button creates a partition (of any
size) in the freed space. Partitions can be resized too. Of course, you
should double-check that you are not deleting the wrong partition.
Again, the rest of the video is useless: let the default choice of "Device
for boot loader installation" and you can reboot as soon as the installation
ends.
