title: Howto merge two avi files using ffmpeg?
body: <p>I'm unable to merge two avi videos together. 
  google is full of below examples:</p>
  
  <pre><code>cat file1.avi file2.avi file3.avi &gt; video_draft.avi
  after appending the data together using cat above, you need to re-index the draft movie like this:
  
  mencoder video_draft.avi -o video_final.avi -forceidx -ovc copy -oac copy
  Now you're video_final.avi file will be right to go.
  </code></pre>
  
  <p>but it doesn't work for me, the first video is converted and that's it.</p>