We’ve been working towards improving the experience on browsers and devices without Flash by moving to an HTML5-compatible video player and H.264 encoded video previews. So far, we’ve transcoded the entire video preview library from FLV to H.264 and rolled out a new player that doesn’t require Flash for playback.
Starting today, authors can choose to upload an H.264 encoded MP4 file for the video preview.
To ensure a consistent file size and viewing experience, both H.264 and FLV uploads go through our transcoding process. In order to achieve the highest quality encoding output we recommend uploading a high quality H.264 MP4 video (with a bit rate >= 2Mb/s).