fix&improve youtube-dl
Thanks.
The problem is: Often when a Website changes, youtube-dl doesn't work anymore. Because of this, even a slightly outdated youtube-dl-Version can cause youtube-dl to not work correctly. As long as the image is rebuilt regularly, it works if the version isn't pinned. (The best option would be for sure to make it fetch the version automatically on build and tag it accordingly - or even to trigger a rebuild on a new version)
The WORKDIR spares me specifying the output-path manually (if I mount the destination in /src as shown in the Doku).
According to dockerized-tools: How will there be taken care to build it using the current version number? Manually? The image will outdate extremly quickly so I am not sure if it makes even sense to add it ...