[pksadiq]

One way would be installing some good GNU/Linux (Mint is good for windows users, or Debian Stretch with GNOME classic mode).

And thus your dad can't install any software he just downloaded from some random website. And the GNOME sofware center is great in Debian Stretch (to be released though, sorry).

create scripts using zenity as a GUI for youtube-dl (and any other command you wish him to run)

Also, I would recommend uBlock to Adblockplus.