No, not quantum physics entanglement (or is it?). Some weird entanglement between my MacBook Air and Mac mini. Both are on Tahoe. Mac mini is in a room where I have my desk and TV (yes, with AppleTV, which is not involved). I also work on my MBA in this room. They’re both on the same WiFi network, although the Mac mini is connected to the network by ethernet cable too.
I can’t describe the situation exactly, it seems to vary a bit (or my memory does), but there is one constant. Sometimes, when I am on the MBA, the mini will start playing a YouTube video. Safari is always open on the mini (was it left with YouTube in the front window? I don’t know). And sometimes I am watching, or have watched, a video on YouTube (I like watching videos about quantum mechanics, which makes this even spookier). Is the video that starts playing on the mini the same one I am/was watching? Again, I don’t know. But if i am not currently watching, the mini starts to play a YT video I had certainly watched.
I know, the facts are not very clear. But the phenomenon is: sometimes, on its own, the mini will start playing a YouTube video.
Possibly… via Universal Control. You may inadvertently be sending your mouse pointer to the other Mac. Possibly via some gesture you do from time to time. If the Mini’s safari window with the YouTube video is live and selected, a tap on your MBA keyboard could start the video playing.
You may have a mischievous partner or child in the house who is savvy enough to tunnel into your other Mini using a VNC app… My son used to pick up my phone and use Jump Desktop to control my Mac, giving him much glee moving my pointer erratically while I got more and more frustrated.
He used to do this with his iMac when his PC owning friends were on it too. Popping up a Notes window and typing messages into while they were online “You are not the owner, why are you on his computer?” and closing the Safari window.
That brought back some memories. When I was in college, I discovered that the early Macintosh text-to-speech engine, MacinTalk, could be coaxed to speak the contents of a text file upon startup. I used to invest far too much time crafting the phonetic spellings of words to annoy my roommate. It was particularly gratifying since he didn’t know how to interrupt playback, so he had to listen to my full “message of the day”. Pioneering stuff in the late 80s!