Short answer
Chrome has picture-in-picture built in: right-click a YouTube video twice and choose Picture in picture. To make it happen by itself every time you switch tabs, use an extension like ytModify.
You're watching a video and need to check something in another tab. The moment you switch, the video is gone from view. Picture-in-picture fixes that: the video floats in a small window in the corner while you do something else.
The built-in way
- On a YouTube video, right-click twice. The first right-click shows YouTube's menu, the second shows Chrome's.
- Choose Picture in picture.
You can also click the media controls icon in Chrome's toolbar while a video plays and press the picture-in-picture button there.
Either way, you have to do it every time.
Make it happen by itself
ytModify, a free Chrome extension I made, does it for you:
- Switch to another tab and the playing video pops out into a small window.
- Come back to YouTube and it slides back into the page.
- A paused video stays where it is.
Switching to another app instead of another tab? Press P first. Chrome only pops a video out by itself when you change tabs, so the key does it before you switch.
You can turn the pop-out on or off, and choose whether it also works on Shorts, in ytModify's settings.
Add it to Chrome
Download it from the ytModify page, unzip it, open chrome://extensions, turn on Developer mode and click Load unpacked.