CCCBib

From the project's README ("Remote control"):

CCCBib takes its commands as webOS launch parameters so the TV needs no open port. It is off by default and you turn it on once in Settings (Playback and then Remote Control). A command is a JSON object. If the app is not running it starts and runs the command and if it is running it gets the command as a relaunch and nothing restarts.

Commands

Command	Parameters
play (or only link)	link must be a media.ccc.de/v/... link (with https://, http:// or without a scheme), nothing else is accepted (no other host, no bare slug or GUID). Optional: start (seconds), aspect (auto, zoom, stretch), subtitle (language code or none), language (audio language code)
pause, resume, toggle, stop	none, stop closes the player
seek	to (seconds) or by (seconds, negative goes back)
mute	value true or false, without it the state toggles
aspect	value: auto, zoom or stretch
subtitle	value: language code or none
language	value: audio language code
add	link, links (list of links) or items (list of {link, position} or {link, percent}). Adds to the watchlist. With a position (seconds) or percent the talk is also put on the in progress list (Continue Watching)
remove	link or links. Removes from the watchlist only, a talk that has progress stays on the in progress list
…

Read the full instructions