Youtube HD

YouTube already provides an option to view higher quality versions for some videos and you can also append "&fmt=18" to the URLs for the other videos. If you add "&fmt=22", some YouTube videos are now available at an even higher quality, which makes the full screen view a very useful option.

+none : standard format - mono, resolution: 320x180
+&fmt=18 : stereo, resolution: 480x270
+&fmt=22 : stereo, resolution: 1280x720

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Directly Download Youtube Videos in Google Chrome, FireFox, Safari and Opera (iUnlockThis: Youtube Hack 2!)

It's easy! While watching the video in Youtube. Just Copy and Paste the Code Below to your Address Bar:
javascript:window.location.href = 'http://youtube.com/get_video?video_id=' + swfArgs['video_id'] + "&l=" + swfArgs['l'] + "&sk=" + swfArgs['sk'] + '&fmt_map' + swfArgs['fmt_map'] + '&t=' + swfArgs['t'];

If the code above doesn't works."Invalid parameters." Use this:
javascript:window.location.href = 'http://youtube.com/get_video?video_id=' + swfArgs['video_id'] + "&l=" + swfArgs['l'] + "&sk=" + swfArgs['sk'] + '&t=' + swfArgs['t'];

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