I think this should be made optional in case there is an alternative update mechanism. It may be hard to believe but not everyone uses docker these days :)

@dop251 yep. you right.
when i was make that i don't think about not docker version and possible permission troubles.

at now i think selfupdate and any another version management must be outside application logic. for self i use that bash script in cron

#!/bin/sh

if [  "$(docker ps -a | grep podsync)" ]; then
	docker exec podsync  youtube-dl --update --verbose
fi

i revert code, but has left changes in dockerfile

I've added optional flag to enable youtube-dl self updated.