Before starting the course, please have VSCode or another code editor installed. Brian is using a font called Dankmono (not necessary to install -- just for those curious), but FiraCode is another great option. This course was written for and recorded by Frontend Masters. The code here is licensed under the Apache 2.0 license and the course notes are licensed under the Creative Commons Attribution-NonCommercial 4.0 International license.
Parcel is an ever evolving project that's just getting better. If you run into problems with it not respecting changes (particularly to your .babelrc or .env files) then delete the dist/ and the .cache/ directories. You can do this in bash by running from the root directoy of your project rm -rf dist/ .cache/ or just by deleting those directories in your editor. This will force Parcel to start over and not cache anything.
See this issue for more specific instructions.
If you run into anything else, open an issue and we'll try to clarify or help.