I found this on WordPress forum, but I don´t know if it helps. I don´t know what to do with the information either: )
“If the theme/plugin is not using the_content() they’d need to add their own support for password protection, which they may not have.
So it looks like you’re using a custom template (page-members-videos.php), that doesn’t use the regular content editor. It’s likely that the template was not built to support password protection. If the template is not using the_content() to render the important content, password protection will not do anything. The template developer needs to add a check for post_password_required().
It would something like:
<?php if ( post_password_required() ) : ?>
<?php get_the_password_form(); ?>
<?php else : ?>
Protected content/template.
<?php endif; ?>
