Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.
I do accept (and appreciate!) pull requests, but please, try to keep them to small, meaningful, isolated changes only that I can go over completely on the stream. Significant outside contributions, as cool as they may be, somewhat defeat the most important part of this project - documenting everything through livecoding. I'm happy to accept small cosmetic changes/bugfixes, but please, consider what the larger audience as a whole might be missing out on when they don't get to see the thought process and resources that went into making the contribution (which is unfortunately what happens whenever I accept a PR).
If you'd like to see a particular library or coding style used somewhere, opening an issue is much preferred over a PR, so we can discuss it beforehand and implement it live. This also keeps people from stepping on each others' toes and implementing the same things (yes, this has happened already).
Issues, especially pertaining to accuracy/bugfixes, are always more than welcome!