如何嵌入youtube频道预告片？

Question

I've searched google, and still can't seem to find an answer. How do I embed/get a youtube channel trailer? I know how to use iframes, and embed single video, but is there a URL or some way to automatically get the URL of the channel trailer (or featured video, usually I keep them the same). If there is no way, I can still just update the video URL each time I change the trailer, but it would be nice if I could to make this automatic. also, I'm using PHP, so using something like curl can also work(as long as it does not slow down page load too much).