Allows to choose a video stream to play.
property OnGetVideoStreamIndex: TRVGetMediaStreamIndexEvent;
This event occurs before playing a video file, if it is played using FFmpeg.
This event may be useful if a video file contains more than one video stream. It is a very rare case.
If the event is not processed, the first video stream is played.
Warning: this event is called in a thread context.
You cannot change a video stream while the video is played: you need to restart video.