Custom YouTube media type - global start time

This custom YouTube media type allows you to use the stop time of the current YouTube video as the start time of the next YouTube video in a XIMPEL subject.

Windows instructions:
- Download the XIMPEL advanced package and extract the contents to the folder "ximpel30_advanced/"
- Download the custom YouTube media type package and extract the contents to the previously extracted folder "ximpel30_advanced/". When asked to replace files, say yes.
- Download and install the latest Flex 3 SDK from http://opensource.adobe.com/wiki/display/flexsdk/Download+Flex+3 
- Configure Flex and make sure that the command "mxmlc" can be executed (also see http://www.installationwiki.org/Installing_Flex)
- In the folder "ximpel30_advanced/" doubleclick on "make_ximpelApp-online_with_SWC.bat" to compile
- When testing locally, adjust your settings at http://www.macromedia.com/support/documentation/en/flashplayer/help/settings_manager04.html

Within a playlist you define the custom YouTube with the <youtube> tag. It has the same syntax as the default YouTube media type. To have any <youtube> video start at the stop time of the previously played <youtube> video, you give the attribute "start" the value "@start". See the playlist "customyoutube.xml" for an example.

See line 52-57 in the code for the extention: CustomYouTubeVideo.mxml
