Why doesn't my mouse pointer disappear while I'm watching full-screen video?

[Windows Central Question]

I have this issue on Edge and Firefox on an XPS 15 9550 running Windows 10.
Happens on all videos from youtube to hbogo etc. I found a "fix" on cnet that says to install a program that will auto-hide the cursor after a specified time. Is that really the only solution? adding another thing to my f-ing task bar??