Last Thursday night, Youtube.com – one of the largest video sharing site which enabled high definition (HD) features without any announcement. Whenever, any user upload a video which is wider than 720 pixels, user will automatically see a option “watch in HD”, so you will get better quality on youtube.

cNet writer Josh noted, “In addition to the quality change in the player, YouTube has updated the embed options to let users chose one of four different sizes–all the way up to 640×505 pixels. There is still no option to embed the video in HD (officially), but you can accomplish this using the method we posted a few weeks back. Also worth noting is that there’s not yet an option to automatically have the HD version play, something which you could tweak in your account settings with the introduction of higher quality clips.”

Youtube didn’t official announced and even they don’t make posts to their blog. But, it’s working on Youtube.com and “for videos uploaded in HD, in the lower right hand corner there is no a link that says “watch in HD” instead of “watch in higher quality,” which is what it used to say.” says on techcrunch.