with open(sys.argv[1], 'rU') as f:
    reader = csv.DictReader(f)
    for row in reader:
        switch_tag = ElementTree.Element('switch')

        attrs = {'src': ("mp4:soundcheck/{year}/{id}/{file_root_name}_256.mp4".format(**row)),'system-bitrate': '336000',}
        attrs = {'src': ("mp4:soundcheck/{year}/{id}/{file_root_name}_512.mp4".format(**row)),'system-bitrate': '592000',}
        attrs = {'src': ("mp4:soundcheck/{year}/{id}/{file_root_name}_768.mp4".format(**row)),'system-bitrate': '848000',}
        attrs = {'src': ("mp4:soundcheck/{year}/{id}/{file_root_name}_1128.mp4".format(**row)),'system-bitrate': '1208000',}
        
        ElementTree.SubElement(switch_tag, 'video', attrs)
        print minidom.parseString(ElementTree.tostring(switch_tag)).toprettyxml()

print minidom.parseString(ElementTree.tostring(switch_tag)).toprettyxml()

I want to look like:

    <switch>
      <video src="mp4:soundcheck/2006/clay_aiken/02_sc_ca_sorry_256.mp4" system-bitrate="336000"/>
      <video src="mp4:soundcheck/2006/clay_aiken/02_sc_ca_sorry_512.mp4" system-bitrate="592000"/>
      <video src="mp4:soundcheck/2006/clay_aiken/02_sc_ca_sorry_768.mp4" system-bitrate="848000"/>
      <video src="mp4:soundcheck/2006/clay_aiken/02_sc_ca_sorry_1128.mp4" system-bitrate="1208000"/>
    </switch>