comments.html.haml

= form_for Comment.new do |f|
    = f.text_area :body
    = f.button t("button.submit")
    
- @video.comments.reverse.each do |comment|
  %div{class: 'comment', id: "comment_#{comment.id}"}
    = simple_format comment.body

source.html

<form accept-charset="UTF-8" action="/videos/84jfu3js/comments" class="new_comment" id="new_comment" method="post"><
div style="margin:0;padding:0;display:inline"><input name="utf8" type="hidden" value="&#x2713;" />
<input name="authenticity_token" type="hidden" value="1J/a93SACpJzTk1q7+oipNDDrxua64Xb+TEEBDA0Nbg=" /></div>  

<textarea id="comment_body" name="comment[body]"></textarea>
  <button name="button" type="submit">Submit</button>
</form>
<!-- Loop -->
<div class='comment' id='comment_'>
  <p></p>
</div>
<div class='comment' id='comment_29'>
  <p>This is my new comment</p>
</div>