Bug: Youtube scenario crash with firefox

Hello,

I'm trying to reproduce the experimentation but I encountered the following error:

```txt
############### https://www.youtube.com/watch?v=k2qgadSvNyU
Traceback (most recent call last):
File "src/run_linux_tlpc.py", line 76, in
run(driver_per_name[name_driver], name_driver, measure_sec=False)
File "src/run_linux_tlpc.py", line 58, in run
scenario()
File "src/run_linux_tlpc.py", line 52, in
lambda: youtube.visit(driver),
File "/home/benjamin/workspace/browser-energy-measurer/src/scenarios/youtube.py", line 40, in visit
driver.execute_script("""
File "/home/benjamin/.local/lib/python3.8/site-packages/selenium/webdriver/remote/webdriver.py", line 879, in execute_script
return self.execute(command, {
File "/home/benjamin/.local/lib/python3.8/site-packages/selenium/webdriver/remote/webdriver.py", line 425, in execute
self.error_handler.check_response(response)
File "/home/benjamin/.local/lib/python3.8/site-packages/selenium/webdriver/remote/errorhandler.py", line 247, in check_response
raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.JavascriptException: Message: TypeError: l is undefined
Stacktrace:
@https://www.youtube.com/watch?v=k2qgadSvNyU:4:5
@https://www.youtube.com/watch?v=k2qgadSvNyU:6:8
```

It seems that the scenario `Youtube` is failing somehow on Firefox.

On my side, I am on Linux and my `Youtube` inside Firefox is using the black theme while Chrome runs the white theme and it works perfectly. It might be related.
The error occurs when the bot must agree to the cookies.

I am investigating.

Thank you.

Best.