advanced-usage: add URL video player widget

Documents bluerobotics/cockpit#515

advanced-usage/index.md

@@ -187,9 +187,9 @@ There are buttons to
 In future it will be possible to set the current vehicle position, and click to guide the vehicle to new
 positions.
 
-##### Video
+##### Video Player
 
-The video widget displays an available WebRTC video stream. BlueOS uses the 
+The video player widget displays an available WebRTC video stream. BlueOS uses the 
 [MAVLink Camera Manager](https://github.com/mavlink/mavlink-camera-manager) to automatically create a WebRTC 
 stream for applicable video streams.
 {{ easy_image(src="video-widget", width=400, center=true) }}
@@ -207,6 +207,18 @@ adding transparent padding at the sides / above+below as necessary
 
 Video recording is possible using a [mini widget](#mini-widgets).
 
+##### URL Video Player
+
+The URL video player widget displays a video from a URL. This is useful for testing IP cameras that are not
+being redirected via BlueOS, but can also be used to display online videos if that is for some reason relevant.
+{{ easy_image(src="url-video-widget", width=400, center=true) }}
+
+Configuration allows selecting which URL to stream a video from, as well as options for whether to play the
+video automatically, whether it should loop when complete, whether it should play sound or be muted, whether
+playback controls should be exposed, and choosing how the video frames should fit within the widget (as
+described in [Video Player](#video-player).
+{{ easy_image(src="url-video-config", width=450, center=true) }}
+
 ##### Mini Widget Bar
 
 The mini widget bar widget is a rectangular container for storing [mini widgets](#mini-widgets).