Well you can, but we do not recommend you to do so. Most smaller blogs are on shared-hosting accounts and videos take a lot of server resource. If your video got tons of traffic, your site is more likely to crash. Second, you are missing out the traffic from YouTube users. We recommend that you pick a third party site such as Youtube, Vimeo etc to upload your videos.
The reason Why You Should Never Upload a Video to WordPress
1-Bandwidth– Uploading videos to your website will cost you bandwidth. Higher quality videos cost more bandwidth. If you allow users to embed it on their own websites, then the bandwidth gets multiplied each time the video is embedded else where. You will probably also have to add more plugins to manage and display your videos. These plugins will also increase your server load.
2-Visibility and Traffic-YouTube is currently the world’s second most used search engine and the third most visited website. This alone compels many website owners to upload their videos to YouTube. Uploading a video on YouTube can bring more viewers than uploading it on your own website. Social networking features of YouTube and other video sharing websites can trigger viral popularity of your videos.
3-Video Quality Optimization is more reason.
4-Easy Sharing-Embedding a video in WordPress is easier. You can share a video uploaded on YouTube or other video sharing sites by just pasting the URL in your blog posts