We should try to validate the user input and give him some examples of video quality.
Some might be unaware of what we mean by quality and may give "720" or "1080" as input, which is wrong. So some sort of validation should be done.
Youtube-dl will not download if the input is wrong, so will another validation be needed? We can add the config to the project, and we can copy-paste some examples from README file, so the user knows how to edit the config.