The content of the file in question is included in the returned data. You are getting the full GitHub view of that file, not just the contents.

If you want to download just the file, you need to use the Raw link at the top of the page, which will be (for your example):

https://raw.githubusercontent.com/someguy/brilliant/master/somefile.txt

Note the change in domain name, and the blob/ part of the path is gone.

To demonstrate this with the requests GitHub repository itself:

>>> import requests
>>> r = requests.get('https://github.com/kennethreitz/requests/blob/master/README.rst')
>>> 'Requests:' in r.text
True
>>> r.headers['Content-Type']
'text/html; charset=utf-8'
>>> r = requests.get('https://raw.githubusercontent.com/kennethreitz/requests/master/README.rst')
>>> 'Requests:' in r.text
True
>>> r.headers['Content-Type']
'text/plain; charset=utf-8'
>>> print r.text
Requests: HTTP for Humans
=========================


.. image:: https://travis-ci.org/kennethreitz/requests.png?branch=master
[... etc. ...]

It depends on the filetype. For non-binaries, you can get the url of the file by clicking on the "raw" button next to "edit" when you have the file open in github. Then, you can just just use curl or wget to download it.

Here is a picture to make things clear:

Then copy the url: