I am afraid that because of the size of the files, you cannot upload videos directly to Add To Event. However, It's easy to add a video which you have uploaded to YouTube or Vimeo to your business profile.
Go to your profile
Login to your account and click on the profile link in the menu:
Choose the option to "Add a video"
Add the video link information
Make sure your videos are set up correctly on Vimeo or YouTube
You Tube set up
For YouTube videos to display, you will need to make sure that the video is listed on YouTube