Gmail has added a new feature today: you can preview YouTube videos, Flickr and Picasa photos all in the email itself without clicking external links.
Previously Google provided this YouTube preview option in its chat service
Google Talk and
Yahoo Messenger also offered a similar service. Google decided if it can be previewed in chat windows why not try the same for emails? So Google has
added the “preview” feature in Gmail.
Now we can see YouTube videos, Picas and Flickr photos and Yelp reviews in Gmail.
To preview them, do the following steps:
1.) Go to Gmail Settings and Click “Labs” tab.
2.) In “Labs” tab, you will see the following four new features in Labs.

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Enable the video, photo preview settings in Gmail.
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3.) Enable the ones you like and click “Save Changes”.
You can watch the previews when your friends or contacts send videos, photos and reviews links in their email.
A photo preview in Gmail will look like the picture below:

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Preview Picasa photos in Gmail.
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A video preview in Gmail will look like the picture below:

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Preview YouTube videos in Gmail.
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If you want your product to have similar preview in Gmail, you can contact Gmail at
this link.