This second synchronization is made by sending HTTPS queries through Tor to several websites and deducing a correct time from their answers. You can see the list of websites that Tails can connect to in *[[!tails_gitweb config/chroot_local-includes/etc/default/htpdate.pools desc="/etc/default/htpdate.pools"]]*.
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It is impossible to use <span class="command">ping</span>`ping` in Tails, because <span class="command">ping</span>`ping` uses the ICMP protocol while Tor can only transport TCP connections.
You can install `youtube-dl` as [[Additional Software|doc/persistent_storage/additional_software]]. *youtube-dl* allows downloading videos from more than [700 websites](https://github.com/rg3/youtube-dl/blob/master/docs/supportedsites.md).