After looking at the patent it’s clear it’s way too vague, generic and obvious. It should never have been granted. (I Am Not A patent Lawyer). For one the XMBC web interface from 2009ish is prior art.
Technically the Kodi remote control app would be in violation of the patent, except it doesn’t use any “back end server system”.
If you replace the words “display” and “video” with “speaker” and “audio” then the Spotify app would be in violation as well, as it allows changing the playback device to any of your logged in devices.
Come to think of it, if you use Firefox on mobile to access YouTube, then “send tab to other device”, and send it to a desktop computer connected to a big screen, it could be interpreted as violating the patent as it’s using Mozilla’s “back end server” to relay the message