Use video upload date as a prefix to filename

> > > Problem:

When downloading a whole Youtube channel with lots of videos, the chronological order of the videos is lost.

This is caused by the filenames that do not contain the dates when the videos were uploaded to Youtube.

> > > Solution:

As an option, make it possible to add the "Youtube video upload date" as a prefix to the filenames of the downloaded videos.

Example:

Before:
An example video.mp4
Another example video.mp4
Fantastic first video.mp4
Second video.mp4

After:
20180131_Fantastic first video.mp4
20180227_Second video.mp4
20180815_Another example video.mp4
20190103_An example video.mp4

Then you can clearly see the chronological order and you can start watching them in the order the videos were made, instead of their alphabetical order, which makes no sense.