In Microsoft PowerPoint, you can embed a YouTube video into your presentation and then allow it to autoplay. To do this, you will slightly modify the embed code when you add it to PowerPoint.
How to Copy a YouTube Embed Code
Step 1
Find your YouTube video and click Share.
Step 2
Click Embed.
Step 3
Click Copy.
How to Add the Embed Code to PowerPoint and Set to Auto Play
Step 1
Paste the embed code from YouTube into Word or another text editor to modify it (you can use Ctrl +V on your keyboard). Then place your cursor inside the code and type ?autoplay=1 to the code. Note the position of the code snippet (right after the video's URL and within the quotation mark). If it's not in the correct position, the auto play will not work. Copy the code (you can use Ctrl +C).
Step 2
Open PowerPoint, then find the screen where you want to add the video. Click Insert, then Video. Select Online Video.
Step 3
Paste the modified embed code into PowerPoint (you can use Ctrl +V on your keyboard). Click on the "insert" arrow to insert into PowerPoint.
Step 4
Your video will be placed on your slide. Use the handles to enlarge the video window.
Now you can open up your slide show and verify that auto play is working correctly.