1.) Create and add a new video upload button next to current upload image button;
2.) Make the new video button work and use the same interface as the upload images option does, to upload embedded videos;
3.) Make it possible that by using the new video upload button videos can be uploaded from: youtube, metacafe, 123video
4.) Make sure the video is displayed and added exactly the same way as images are added as a tweet;
5.) Using the same style and layout as the current image option.
Build in a pre content check that only embedded videos can be added using this option not images.