The Video Track can be added on the Director Group only and works closely with the Video Clip which is the only type of clip able to add to a Video Track.
Video Clips are the only clips that can be added to the Video Track.
The Blend In and Out will affect the alpha of the video, which is also multiplied by the alpha set in the Video Track. The video to play can be set in the Video Clip field. As with all Slate clips that wrap-up a sub-clip (like in this case a video), you can offset the sub-clip start time in relation to the Slate clip start time, and you can use the buttons at the bottom to make the length of the video clip match certain loop times of the video it is set to play.