For Chrome, writing an extension that will invert images and videos
seems easy enough (via copy and paste).

If so, that's just about everything to make a complete dark windows
theme, except for uninverting still images in Windows outside of
chrome. It's really luck that VLC media player just happens to include a
option to persistently uninvert videos. Since picture/photo viewers do
not even do that, I can't imagine any other video player doing that.

There are some Chrome extensions to invert pictures and videos, but for
some strange reason they do not simply invert, they add some tint. One
chrome extension appears to do videos well, but it doesn't do pictures,
and it includes stuff that isn't necessary.

I see no difference in CPU or memory usage when inverting or uninverting
videos.


--

Chrome

manifest file...
{
"manifest_version": 2,
"name": "invert videos and images",
"version": "1.0",
"content_scripts": [
{
"matches": [
"all_urls"],
"js": ["content.js"]
}
]
}
javascript file...
javascript:var imgs=document.getElementsByTagName("img");for(i=0; i
imgs.length;i++){imgs[i].setAttribute("style","-webkit-filter:invert
(100%)");};
javascript:var vids=document.getElementsByTagName("video");for(i= 0;i
vids.length;i++){vids[i].setAttribute("style","-webkit-filter:invert
(100%)");};

Won't do all items of concern, but it can be edited.