Why can't I add video to my request?

Since they are costly to host, videos can only be added directly to prized requests. If you want to include videos in your request, you therefore have two options: 

1. Check the Will you award a prize to the best answers? checkbox in the Budget section of the request creation page. This will enable the video upload option. And you'll have to fund the award before your request can be published. 
2. You can always include links to media hosted elsewhere in the Context of your request. This option doesn't require you adding a prize to the request but is also less direct, since honswerers will have to leave the site to access them.