Youtube high quality videos into xml playlist

I'd like to load high quality videos from Youtube by an xml playlist, but I can't
This is my playlist

<?xml version="1.0" encoding="utf-8"?><playlist version='1' xmlns='http://xspf.org/ns/0/'>
<trackList>
<track>
<creator>Artist</creator>
<title>NBA Highlights</title>
<location>http://www.youtube.com/watch?v=r-o_O_C5F4Y&amp;fmt=18</location>
<image>http://img.youtube.com/vi/r-o_O_C5F4Y/1.jpg</image>
</track>
<track>
<creator>Artist</creator>
<title>NBA Highlights</title>
<location>http://www.youtube.com/watch?v=yv2OBorhKTk&amp;fmt=18</location>
<image>http://img.youtube.com/vi/yv2OBorhKTk/1.jpg</image>
</track>
<trackList>
</playlist>

I added to every url '&fmt=18' and set quality to 'true'
However, I continue to watch standard quality videos
Any ideas?