Snapchat is making it easier to share YouTube videos within your snap or story, letting you bypass the process of copying, pasting, and attaching the video as a link (via Android Police). The feature is available on both Android and iOS.
Now all you need to do is navigate to YouTube, hit the “Share” button, and then select “Snapchat.” Snapchat will open, and the video will automatically appear in your camera as its own sticker, showing the name, thumbnail, and creator of the video. After you take your picture or video, you can play around with the size of the sticker, rotate it, and place it anywhere on the screen. Anyone who views your snap or story can click on the link and view the video within the YouTube app or in their web browser.
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Source: TheVerge