Hashicorp has at least two places in their website from which you can install Terraform. Each one has the same instructions, just a different layout. The page I use in the video is here:

https://developer.hashicorp.com/terraform/tutorials/aws-get-started/install-cli

You can also install it from here:

https://developer.hashicorp.com/terraform/install

The script to install it is here:

wget -O- https://apt.releases.hashicorp.com/gpg | sudo gpg --dearmor -o /usr/share/keyrings/hashicorp-archive-keyring.gpg

echo "deb [signed-by=/usr/share/keyrings/hashicorp-archive-keyring.gpg] https://apt.releases.hashicorp.com $(lsb_release -cs) main" | sudo tee /etc/apt/sources.list.d/hashicorp.list

sudo apt update && sudo apt install terraform