Plex Web 3.17.2 break PiP
Looks like the latest update to Plex Web 3.17.2 kills pip support for Plex Looks like a big webUI update, so suspekt a lot up updates to the webapp
Just wanted to second loss of this valued feature.
Yes I also miss this.
Wanted to use PiP today, went to install PiPTool again, and noticed Plex/Web doesn't work any more. I miss it too.
Same for me — Was sad that it worked so well and now it's broken :/
Small work around for the time being is to drag the video element up to the top of the body in the dev elements console, then delete everything else below, then click the PiP extension and click the video.

Is the class for the video player 'VideoContainer-videoElement-1EaMR' for everyone else? I see that's what it is in the screenshot there and that's what it's called for me. I'm trying to patch the plex support but I'm not super experienced with node.js or working with Plex.
I can confirm the class "VideoContainer-videoElement-1EaMR" also. I used the inspector to move the video tag and it worked. Hopefully that'll help you target it.
I'm not confident that the "1EaMR" portion of that class will remain after any subsequent deploys by Plex to the web app, even if the code is unchanged for that specific node so the fix might be fairly brittle. If there's any way to be slightly more generic, I'd give that a try first.
You could just look for the first video element
document.getElementsByTagName('video')[0].webkitSetPresentationMode("picture-in-picture")