Watched the video and can upload photos to MY PHOTOS but can't copy/paste from My Photos to a New Message. Tried both CTRL C/ CTRL V and right click copy/paste but the image won't paste to the message composition window.

Copy/paste works in Gmail so something about my browser and Hangouts New Post window apparently not compatible. Using Chrome. Will try Firefox -sometimes there are browser issues.

:Later...tried EDGE browser and same results - image is not pasting to the Message Comp window. I had also done a restart on the PC. Running out of ideas. Will watch the video one more time as he had more than one way to move images