Not quite an XBox, but my PS4 does this quite nicely out of the box with Plex. As an aside I'd also highly recommend "Sofaplay" which is by far the easiest way

Not quite an XBox, but my PS4 does this quite nicely out of the box with Plex. As an aside I'd also highly recommend "Sofaplay" which is by far the easiest way I've found to beam video to my Samsung Smart TV from my MBP. Literally "just works" dragging a file onto a drop-target. Does the transcoding and everything with '0' fuss.