Copyright laws: All images categorized as public domain can be downloaded for personal use: copying, distribution, adaptation, performance, and display. A work is considered public domain when the author has placed their piece in that category or the time of copyright has expired. Some works that are not copyrightable are United States government works, facts, and works that lack originality.Unless you see something is in the public domain, assume it is protected under copyright and cannot be legally downloaded for personal use until the appropriate time period has passed.
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Searching for multimedia (visual)
Picsearch allows you to search for images and animations through words. Matching results are displayed as small images with links and information. Options from the advanced search restrict results by image type, by color or black&white, and by image size.
Try Picsearch by entering your words here and pressing Search!
If you'd rather browse pictures, Picsearch offers an Image Directory of categories such as Animals, Classic Cars, Flowers, Landmarks, and Legends.
Newer community-based picture tools like Flickr allow you to share your own pictures and search for and comment on pictures taken by others. You can use keywords and browse photos by categories or tags. You can also search Flickr photos by color through the Color Fields Colr Pickr.
Many of the images found using the tools above will be protected by copyight laws, so you need to take care in how you use the images. However, there are lists of resources that have images in the public domain that you can use.
blinkx TV touts itself as the "world's largest video search engine" with content from the Web and from many major networks. The search page offers a keyword search and a slider bar that allows you to change the way the results are sorted (by date on the left of the slider, and by relevance to the keywords on the right). Like several of the image searches mentioned above, blinkx also provides a "Safe filter" to help filter out adult content.
Singingfish is an excellent search engine for audio and video clips through a keyword or phrase into the search box and Singingfish will return a list of results. The matches are labeled by icon to show if itís an audio or video clip.