import selenium
from selenium import webdriver

url = "http://url"
profile = webdriver.FirefoxProfile()
profile.add_extension('browsec@browsec.com.xpi')
#profile.add_extension("C:UsersursAppDataRoamingMozillaFirefoxProfilesabc.defaultextensionsbrowsec@browsec.com.xpi")
driver = webdriver.Firefox(firefox_profile=profile)

if __name__ == "__main__":
   driver.get(url)
   driver.wait(5)
   driver.quit()

profile.add_extension('browsec@browsec.com.xpi')

profile.add_extension("C:UsersursAppDataRoamingMozillaFirefoxProfilesabc.defaultextensionsbrowsec@browsec.com.xpi")