I'm pretty new to chrome extension development, I'm trying to make a better PiP (Picture in Picture) that doesn't have the maximum window size limitation.

I'm using this extension as reference, it basically behaves the same way as the default PiP works with video.requestPictureInPicture() which is what I don't want to use because extension popup has limited window size.

Instead, I have a index.html page with my extension that is loaded with window.open in background.js, this index page will have a video element that the HTMLVideoElement is passed to.

I've tried using chrome.runtime.sendMessage to send the video to the video.js that the index.html page loads, but this doesn't seem to work with a HTMLVideoElement? I read elsewhere that I should do JSON.stringify/JSON.parse for this object but that results in undefined.

Relevant manifest.json:

"background": {
    "service_worker": "background.js"
},
"content_scripts": [{
    "all_frames": true,
    "js": [ "content.js" ],
    "matches": [ "*://*/*" ],
    "run_at": "document_start"
}],
"web_accessible_resources": [{ 
    "resources": [ "index.html" ],
    "matches": [ "*://*/*" ]
}],
"manifest_version": 3,
"permissions": [ "storage", "scripting", "activeTab", "tabs" ],

content.js:

const videos = new Set();

window.addEventListener('canplay', e => {
    if(e.target.tagName === 'VIDEO') {
        videos.add(e.target);
        chrome.runtime.sendMessage({
            method: 'VIDEO_PLAYING'
        });
    }
}, true);

background.js:

await chrome.scripting.executeScript({
...

    var win = window.open(chrome.runtime.getURL('index.html'), 'PiP');
    win.focus();
    chrome.runtime.sendMessage({
        method: 'VIDEO',
        data: JSON.stringify(video)
    });

video.js: - this is the js that is just included on index.html

const onMessage = (request, sender) => {
    if(request.method === 'VIDEO') {
        var data = JSON.parse(request.data);
        console.log(video.src); //undefined
    }
};
chrome.runtime.onMessage.addListener(onMessage);

Maybe my method of going about doing this is entirely wrong. Are there other ways I can pass such objects to index.html like this?