I've just finished to upload a new test comparing the results that we get from the video and object elements. In this test I've used a Flash video (a file with the extension flv) using video/x-flv as content type. Results are inconsistent due to the particular file format chosen for the test, but I guess that when a browser doesn't have all the codecs and plugins installed it will always show everything blank. Further, I've also tried to use video to include a remote file from YouTube, but I didn't get what I wanted. There are two things to keep in mind: codecs and content type. Although many browsers are able to recognize the content type of a particular file, it's always better to choose an appropriate media type for that purpose. The problem is always one: what is the correct media type for the browser X? More tests are coming.