Make sure you are using the Chrome browser.

While playing a video (either a standalone video or a video within a presentation), click the cast button that appears in the video.
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Select your Roku device from the list that appears.
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Download the app and Log in. Learn more here.

In the app, click the casting icon.
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Select your Roku device from the list that appears.
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Download the app and Log in. Learn more here.

In the app, click the casting icon.
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Select your Roku device from the list that appears.
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You are connected now. You can just open any video or presentation and start watching.
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