if(empty($paid)){
    if(isset($users_credits)){
        if($credits > $users_credits){
            $errors[] = 'Not enough credits for this action. Visit credits page from your profile to charge up your account!';
        }        
    } else {
        $errors[] = 'You need to login before you can watch this video';
    }    
}

$smarty->assign('paid', !empty($paid)?$paid:false);