The video block allows you to upload and embed video into your post or page.
For WordPress.com sites the video block is supported on the WordPress.com Premium, Business, and eCommerce plans. If you do not wish to upgrade, you can upload your video to a free service like YouTube and embed the video onto your site.
Get started by clicking the + Inserter icon 
at the bottom-left corner of the screen and select the Video Block from the blocks list
Once you add the block tap the Add Video option to select a video from your device or Media Library.
Once the vide is added you can tap on the cogwheel icon to see the video options
