QtWebKit and QtMultimediaKit

[a.v.mich]

Hello.
I need help in including support for video and audio tags in qmlwebkitplugin for Windows.
I've built QtMobility (module multimedia), rebuilt QtWebkit and qmlwebkitplugin.
After opening page with video and audio tags in declarative demo-browser I've got controls with right time at audio tag, poster and control with null time at video tag and no music or video. Only controls. VideoWidget from examples in QtMobility correctly plays video and audio file. How can I see what codecs are available for WebView and how can I make sound and video works?

Thanks for any thoughts.