I want to access with Selenium (through) Python, a URL that demands authentication.
When visit the URL, manually a new authentication window pops up, on which I need to fill in a username and password. Only after clicking on “OK” this window disappears and I return to the original site.
As I want to visit this URL on an interval base to download information and want to automatize this process in python.
In my current effort I use Selenium, but none of the examples that I found seem to do what I need. Thinks I tried but do not work are:

driver.get("https://username:password@somewebsite.com/")
selenium.FireEvent("OK", "click")
driver.find_element_by_id("UserName")

I do not know the actual element id’s
What I did manage is to load my Firefox profile that stores the authentication information, but I still need to confirm the authentication by clicking “ok”.
Is there any way to prevent this screen to pop up? 
If not how to access this button on the authentication form, from which I cannot obtain id-information?
Using driver.get("https://username:password@somewebsite.com/") should directly log you in, without the popup being displayed,
What about this did not work for you?
EDIT

I am not sure this will work but after
driver.get("https://username:password@somewebsite.com/") 
Try accepting alert.
For the alert - @driver.switch_to.alert.accept in Ruby or driver.switchTo().alert().accept(); in Java
How to Submit Https authentication with Selenium in python