Argparse and better dowanload folder structure

Hello Tayseer,

I replaced the sys.argv and the manual printing of usage with the "argrparse" module.

I also organized the downloads. Instead of downloading the presentation in the same folder as the code, I made the script create a "downloads" folder, then it creates another folder inside it with the title of the presentation and the presentation is downloaded there.

It works for the html and the slides, but I didn't get yet to test it with the video.