Player: remote control while casting

Shows the receiver's position with play/pause, ±30 s and a scrubber;
a seek restarts the relay where asked.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/docs/USERGUIDE.md b/docs/USERGUIDE.md
index ad51982..1790475 100644
--- a/docs/USERGUIDE.md
+++ b/docs/USERGUIDE.md
@@ -395,7 +395,10 @@ resume.
 **The desktop and Android applications.** A film playing in the application can
 be sent to a cast-capable TV or dongle on the same network: *Cast to device* in
 the player, pick one from the list. On a phone, the film goes on playing silently
-on the phone while the TV shows it, and the screen can be turned off. Devices appear as they answer, usually within a couple
+on the phone while the TV shows it, and the screen can be turned off. While a
+TV plays the film, the player becomes its remote: the position shown is the
+TV's, with play/pause, 30-second jumps and a slider to go anywhere in the film.
+Devices appear as they answer, usually within a couple
 of seconds; the search carries on for a few more, for a TV that is still
 waking up.