I think Lars skipped some steps because they are not necessarily relevant to Plutus. It's more general and will depend on your operating system. Assuming you're running Linux like Lars, follow the steps below. Note that you can be in a Nix shell for this, but you don't have to be. This is just downloading a binary and putting it on your PATH.
In the video, Lars cuts while on this page:
https://hydra.iohk.io/build/9941098#tabs-constituents
From there, you should click on cardano-node-linux (job #9941151)
Click on cardano-node-1.33.0-linux.tar.gz binary distribution to download the tarball
Make a permanent directory in which to store the binaries
mkdir ~/cardano-node
Extract the tarball contents into the directory. Note that your downloaded tarball may be in a different directory depending on how your system is configured.
tar -xf ~/Downloads/cardano-node-1.33.0-linux.tar.gz -C ~/cardano-node
At this point, you can execute cardano-node
cd ~/cardano-node
cardano-node --version
But you probably want to be able to run it from anywhere, not just in that one directory.
To do that, make sure the ~/cardano-node directory is always part of your PATH when you log in by editing ~/.bashrc and adding the following line
export PATH="$HOME/cardano-node:$PATH"
While you're editing .bashrc, save yourself some time later by adding this environment variable, too. You'll need it later. Note: Change the path if your plutus-pioneer-program directory is somewhere else.
export CARDANO_NODE_SOCKET_PATH="$HOME/plutus-pioneer-program/code/week03/testnet/node.socket"
Finally, source .bashrc to make sure the PATH and that environment variable are set in your current session
source ~/.bashrc
At this point, you'll be at the same point Lars is in the video.
