You need to use a third-party video hosting service to store and serve video. These services are built specifically for serving high quality video, and their accounts are free. Start by creating an account and uploading video to a video-hosting site. After you have uploaded your video clip to an online video service, locate and copy the embed code for the service’s video player. Each provider will have code that looks slightly different.  

Next you can add your video as a standalone story. Click on New under the Stories tab on the left navigation bar in the WordPress dashboard. Then enter the Title for the article. If you have a story or short explanation of your video, paste that in the main text-editing window, but do not add your video in this window.

Paste your video embed code in the custom field labeled Video Embed Code below the main text-editing window. If you want to give credit for the video, add a name in the Video Credit Line Custom Field box. If there is a staff profile for this name, this video will automatically be linked to that staff profile.

More information on how to complete this process can be found here: https://support.snosites.com/hc/en-us/articles/115001588774-How-to-Add-Videos