Pagination in URLs only works for the “main” query. What you’ve created is a secondary query, so WordPress doesn’t “know” about it in such a way that the application would be able to create pagination. If you use a secondary query (like your example) it’s up to you to do the pagination stuff manually.
Rather than create a new query, I’d suggest you alter the “main” query with the pre_get_posts
hook. Example:
<?php
add_action('pre_get_posts', 'wpse89413_pre_posts');
function wpse89413_pre_posts($query)
{
// make sure you're on the blog page and altering the main query
if (is_home() && $q->is_main_query()) {
$query->set('post_type', array('post', 'videos', 'music'));
$query->set('tax_query', array(array(
'taxonomy' => 'content',
'field' => 'slug',
'terms' => 'indy',
'operator' => 'NOT IN'
)));
}
}