A YouTube downloader made in Python.
None needed. py-yt is completely portable. Just run the exe.
How this works is the python script collects info about what you want to download and how to do it, then it opens a browser to /endpoint/ or /endpoint/audio/, depending on the format of the download. The endpoint will then get the media and save it. You can modify it, but the modification MUST be under the GNU General Public Licence v3.
Not possible sorry. (You can if you want, but you have to de-obfuscate and decompile it.)