Query Multiple Custom Post Types & Exclude a Taxonomy Term

You should have a look at the arguments of WP_Query. The following arguments should be what you need. Note that tax_query takes an array of arrays.

$args = array(
  'post_type' => array( 'post', 'videos', 'music' ),
  'tax_query' => array(
     array(
       'taxonomy' => 'content',
       'field'    => 'slug',
       'terms'    => 'indy',
       'operator' => 'NOT IN' 
     )
   )
);

$myquery = new WP_Query( $args );
while( $myquery->have_posts() ):
  $myquery->the_post();
  # do your stuff here
endwhile;