allow choice between playbin3 and playbin2 for HLS video

README.md

@@ -7,7 +7,9 @@
     YouTube app to stream video. (You may need to wait until
     advertisements have finished or been skipped before clicking the
     YouTube airplay icon.) **Please report any issues with this new
-    feature of UxPlay**.
+    feature of UxPlay**.   _The default video player for HLS is
+    GStreamer playbin v3: use "-hls 2" to revert to playbin v2 if
+    some videos fail to play_.
 
 ***NEWS***: macOS Sequoia 15.2 has an AirPlay bug: update to macOS 15.3
    for mirroring  screen with UxPlay.
@@ -961,10 +963,14 @@ The "-h265" option changes the default resolution ("-s" option) from
 1920x1080 to 3840x2160, and leaves default maximum framerate ("-fps"
 option) at 30fps.
 
-**-hls** Activate HTTP Live Streaming support. With this option YouTube
+**-hls \[v\]** Activate HTTP Live Streaming support. With this option YouTube
 videos can be streamed directly from YouTube servers to UxPlay (without
 passing through the client) by clicking on the AirPlay icon in the
-YouTube app.
+YouTube app.   Optional \[v\] (allowed values 2 or 3, default: 3)
+allows selection of the version of GStreamer's
+\"playbin\" video player to use for playing HLS video. _(Playbin v3
+is the recommended player, but if some videos fail to play, you can try
+with version 2.)_
 
 **-pin \[nnnn\]**: (since v1.67) use Apple-style (one-time) "pin"
 authentication when a new client connects for the first time: a