There are tons of really useful command-line multimedia utilities available for Linux (and other platforms). cmus, youtube-dl, castero are to name just three essential command-line multimedia apps that frequent my shell.
If you’re looking for another way to watch YouTube videos, you should also check out youtube-viewer. It’s billed as a semi-automatic tool for browsing YouTube. It has lots of advanced options, including search-based filtering on various criteria and support for selecting videos matched by a regular expression.