Resolution
Remove the ? before the m and use variable $1:
RewriteRule ^film/([a-z0-9\-]+)/?$ index.php?p=filmes_v&m=$1 [NC]
The htaccess will be as follows:
<IfModule mod_rewrite.c>
  RewriteEngine On
  RewriteRule ^film/?$ index.php?p=filmes [NC,L]
  RewriteRule ^film/([a-z0-9\-]+)/?$ index.php?p=filmes_v&m=$1 [NC]
</IfModule>
Note that within [] in regular expressions it is recommended to escape -, because they are used in the syntax of the expression, as an example [a-z] indicating of a until z. - @Guilhermenascimento
Links and Scripts
Using URL friendly you accurate can use absolute paths or just reference the files indicating a / at the beginning of the way:
<link href="http://meudominio.com/css/meucss.css">
<!-- ou -->
<link href="/css/meucss.css">
<a href="http://meudominio.com/contato">
<!-- ou -->
<a href="/contato">
<script src="http://meudominio.com/js/jquery.min.js"></script>
<!-- ou -->
<script src="/js/jquery.min.js"></script>
Relative Paths
Heed: Relative paths has to be initiated with / which indicates the site root, because if the current page has an address similar to http://meudominio.com/contato and the user click on a link <a href="sobre">Sobre</a> he will end up at the address http://meudominio.com/contato/sobre.
A very interesting resource to use with relative paths is the RewriteBase. For example imagine that you have a blog and it’s structured more or less like this on the server:
/root
| - /www
|   | - /blog
|       | - /css
|       | - /js
And the URL to access this blog is http://meusite.com/blog/ then in all your code you will have to reference your scripts and links using the semi-relative URL /blog/.
<link href="/blog/css/estilos.css" rel="stylesheet" type="text/css">
<script src="/blog/js/scripts.js" type="text/javascript"></script>
<a href="/blog/sobre">Sobre</a>
But if in the htaccess of Blog is defined the RewriteBase for blog, will no longer need the /blog/ in the URL:
RewriteBase /blog/
And your Urls can stay:
<link href="/css/estilos.css" rel="stylesheet" type="text/css">
<script src="/js/scripts.js" type="text/javascript"></script>
<a href="/sobre">Sobre</a>
And so if at some point you decide to change the address http://meusite.com/blog/ for http://blog.meusite.com just need to change the RewriteBase for / or remove it:
RewriteBase /
So you don’t need to change all the links removing the one /blog of Urls. :)
You can also have this feature through tag base. But I prefer the htaccess.
Other means
A very interesting way to make friendly Urls is the way I call it Dynamic Friendly Urls, the implementation would be so:
<IfModule mod_rewrite.c>
  RewriteEngine On
  RewriteCond %{REQUEST_FILENAME} !-d
  RewriteCond %{REQUEST_FILENAME} !-f
  RewriteRule ^(.*)$ index.php?uri=$1
</IfModule>
This way you can treat the URI in PHP to receive as many variables as you want, example:
$tmp = !empty($_GET['uri']) ? $_GET['uri'] : 'home'; // Página padrão home
$uri = explode('/', $tmp);
$vars = Array();
if (count($uri) > 1){
    $key = 'page';
    foreach ($uri as $val) {
        if (is_null($key))
            $key = $val;
        else {
            $vars[$key] = $val;
            $key = NULL;
        }
    }
}
In the previous example, you can send the URL http://meudominio/catalogo/categoria/eletrodomestico/preco/100~500/voltagem/220 and you would have the following structure in the variable $vars:
page        => catalogo
categoria   => eletrodomestico
preco       => 100~500
voltagem    => 220
So the first argument is always the page and the following are any parameter you want, in any order and should always be
sent in pairs chave/valor. This form is quite useful for making filters.
Model MVC
Using this concept it is simple to apply a MVC model that would be:
controller/action/demais/parametros
For example:
$tmp = !empty($_GET['uri']) ? $_GET['uri'] : 'home'; // Página padrão home
$uri = explode('/', $tmp);
$vars = Array(
    // Controller `index` caso não tenha parâmetros na URI, caso tenha armaza e remove-o da URI
    'controller'   => (count($uri) > 0 ? array_shift($uri) : 'index'),
    // Action `index` caso não tenha parâemtros na URI
    'action'       => (count($uri) > 0 ? array_shift($uri) : 'index'),
    // Demais parâmetros
    'params'       => Array()
);
$key = NULL;
if (count($uri) > 1){
    foreach ($uri as $val) {
        if (is_null($key))
            $key = $val;
        else {
            $vars['params'][$key] = $val;
            $key = NULL;
        }
    }
}
Thus accessing the URL:
www.meudominio.com/sobre/empresa/page/3
We will have the following result:
$vars = Array(
    'controller' => 'sobre',
    'action'     => 'empresa',
    'params'     => Array(
        'page' => '3'
    )
);
							
							
						 
Change the line:
RewriteRule ^film/([a-z0-9-]+)/?$ index.php?p=filmes_v&?m=$1 [NC], about CSS would be better to post as you are doing.– Papa Charlie
Thank you @Papacharlie, the $2 was my own distraction.
– xdam98
@Kaduamaral, that was my problem, I managed to solve, thank you.
– xdam98
By the way, the CSS problem from this I think I can solve :)
– xdam98