While Manifesto is capable of displaying uploaded video in much the same way it handles images, the best solution is not quite so easy. Different platforms and different browsers require that your video be in different formats (MP4, OGV, WEBM).
So unless you want to create multiple versions of your video for full compatibility, it is much easier to take advantage of one of the major video hosting platforms (usually YouTube or Vimeo). Those services automatically handle the generation of multiple formats for your video, and they serve the appropriate format to the right browser.
Step 1: From YouTube, for example, go to the page where the video lives. (Uploading your video to YouTube is an exercise outside the scope of this article). Click on the "Share" link below the video.
Step 2: A modal window will open, and you want to select the "Embed" option, as below.
Step 3: This will open another modal window with a preview of the video, and some HTML code on the right.
Click the "Copy" button to copy all of the HTML code.
Step 4: Return to the Manifesto page where you want to embed the video.
You cannot paste the code directly into the editor. Because it contains HTML codes, you must paste the code into the HTML editing window rather than the WYSIWYG editor. So click the <> button at the end of the toolbar.
Step 5: Paste the code you copied from YouTube into the correct position in your HTML content. You may have to hunt around a little bit, ignoring the various HTML tags to figure out exactly where to place it. You should always embed the code outside of any <p> paragraph tags, because the video will create its own block in the text.
Step 6: When you click "OK" to close the HTML editor, you will be returned to the WYSIWYG editor, and you can immediately see your video rendered in the window.
Step 7: Save your page, and now you have a cross-platform video embedded on your site!