That will cause major problems for your Windows installation. Specifically, it will not be able to boot.
First, you should remove the extra FAT32 partition and use only the Windows one. Windows and Linux can share the EFI partition. No need to make a second FAT32 partition or overwrite these files, or otherwise make any changes to the EFI partition. It just needs to be mounted during the installation and the needed files will be added right alongside what is already on there.
Next, you should resize the Windows partition if you need to make space on the disk. It is best to resize Windows from within Windows itself. If you try to do it from Linux you may need to repair the NTFS filesystem afterward from the Windows rescue environment.
It may be worth reconsidering this strategy since you will be using Btrfs. /home will be installed in a separate subvolume than / automatically with the default subvolume layout. Keeping them on the same partition in separate subvolumes will allow them to stay separated, but still allow each subvolume to expand to whatever size it needs to on the partition. If you divide up the partition, you will have two separate Btrfs filesystems with a pre-determined maximum size (which you may regret when one file system becomes full), for arguably little or no benefit.
Anyway, after you have that all figured out:
I’m not going to watch that video so I have no idea what it says, but these will be the basic steps you will follow if you want to use the manual partitioning option:
Select the EFI partition and click on Edit. Be very careful with the selections here. You want to keep the contents of the EFI partitions–do not format it or you will lose the Windows boot files.
EFI partition:
- Content: Keep
- Mount point:
/boot/efi
Next, select the partition to install the main system and click on Edit. This partition should be mounted at /. Choose the Btrfs filesystem, and this time you will choose to format it.
Btrfs partition:
- Content: Format
- Mount point:
/
Finally, if you do wish to install /home on a separate partition you will need to click on that partition, and one more time click Edit, choose Content: Format and Mount point: /home.
If you decide not to go with a separate partition for /home, you may be able to just use the “Install alongside” option in the installer instead of manual partitioning. I would guess this is the option most people choose for setting up a dual-boot system like this.
Here is another completely different strategy for this kind of setup. It looks like a little bit more work and does involve reinstalling Windows after the partitions are set up, but seems interesting and may be worthy of consideration if you haven’t made up your mind on your approach yet: