If you are looking to download some high-res video clips from YouTube for your next presentation, try this easy trick that will only display high quality videos in the search results.
Go to Google.com, type your search phrase and append the following paramters your search query.
site:youtube.com "watch in normal quality watch in high quality"
To illustrate this with a real example, a search for "cnn hologram" related videos on YouTube would look something like this on Google:
cnn hologram "watch in normal quality watch in high quality" site:youtube.com
This works because YouTube adds a small "watch in high quality" link beneath their video player if the video you are watching is available as high resolution.
When you click that "high quality" link, it is replaced by "watch in normal quality" so the two strings are really close in the HTML source and that helps us filter low quality videos from search.