Summarize the following:
To do so:  Go to YouTube in a browser of your choice. Open the video you want to embed. Click the video's address in the bar at the top of the browser window. Click the Edit menu item. Click Copy in the drop-down menu. Double-click the PowerPoint presentation file to open it in PowerPoint.  If you haven't yet created the presentation, just double-click the PowerPoint icon, which resembles a white "P" on an orange background. On the Mac version of PowerPoint, there is no built-in way to embed a YouTube video; however, you can download a free add-in from Microsoft to embed videos. Click a slide on the left-hand side of the PowerPoint page. It's in the orange ribbon near the top of the PowerPoint window. You'll find this option in the toolbar below the orange ribbon. Doing so will open the Microsoft store. Type web video player into the search bar in the upper-left corner of the page and press ⏎ Return. It looks like a white "Play" button on a red background. This is a green button to the right of the Web Video Player app icon. Doing so will add a Web Video Player box to your current PowerPoint slide.  If prompted, first click Open in PowerPoint and then click Trust this add-in. You may have to insert Web Video Player manually by clicking the Insert tab, clicking My Add-Ins, clicking Web Video Player, clicking the Insert button, and then selecting Web Video Player by clicking the My Add-Ins section again and clicking Web Video Player. Click the white box inside of the Web Video Player interface on your slide, then click Edit in the top-left corner of the screen and click Paste. The video's link will appear in the box. Doing so will embed the selected video in the Web Video Player window in your PowerPoint slide. Press ⌘ Command+S to save your changes to your presentation. If this is a new presentation, a window where you can name your file and select a save location will pop up.

Summary:
Copy the link for your YouTube video. Open your PowerPoint presentation. Go to the slide where you want to insert a video. Click the Insert tab. Click Store. Search for the "Web Video Player" app. Click the Web Video Player icon. Click ADD. Paste your YouTube video link into the Web Video Player box. Click Set Video. Save your work.