YouTube videos are now served in WebM format as reported by James Zern, Software Engineer, on the company blog. Now the vide site is transcoding all new videos into the WebM format, as well as other supported formats, which include MPEG4, 3GPP, MOV, AVI, MPEGPS, WMV, and FLV.
In the announcement, YouTube says they are working to transcode the rest of the YouTube catalog.
read more