Provided you don’t need to reproduce stereo 360 videos but just plain (mono) 360 videos, you can follow the method explained here: UE4 Media Player to Render a Media Texture - YouTube, but instead of projecting your video onto a flat mesh, you project it onto a sphere with inverted normals (you can create it in Maya or Blender, or use the skysphere mesh part of the Engine content).
Then you place your VR camera exactly at the center of the sphere, facing the right direction according to the center of attention in your video, and play the movie. That’s pretty much it.