Replace a webcam with a video

Hello, do you know any free method to create a virtual webcam through which you can stream a video? The software found on “Camastuce.com” seems to match what I'm looking for, but it looks like a scam (ads for porn sites, using the informal "you," spontaneous mention of “MSN” and especially, requesting a code via SMS). Is there a more "serious" software available?
Thank you for your answers.

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