Hey Venkatesh,
I'm assuming you're talking about video milestones at 25% intervals - I was able to use the DTM based direct call rules to set the appropriate video eVars and events for each 25% milestone (one for each), however you will still need to integrate with your video player to trigger the appropriate milestone rule as the video time passes each 25% milestone.
I've attached a screenshot of the direct call rule for the first 25% milestone as a reference. Perhaps one of the Adobe guys can confirm whether this is the best approach, however it worked for me :)
For creating and setting the actual video variables and events themselves, the online documentation is pretty good - see http://microsite.omniture.com/t2/help/en_US/sc/appmeasurement/video/, http://microsite.omniture.com/t2/help/en_US/sc/appmeasurement/video/video_analyst.html and http://microsite.omniture.com/t2/help/en_US/sc/appmeasurement/video/video_developer.html.
Good luck!
Cheers, Jez
