How do i slow down a video in my composition? defaultPlaybackRate = 0.3;

I have a mp4 file video that i am using in a composition. I would like to slow it down and am having trouble doing it in my composition.

I converted the video layer to a symbol and named it hoverbordVideo.

I assumed this would work: sym.getComposition().getStage().getSymbol("hoverbordVideo").defaultPlaybackRate = (0.3);

What am i missing?