1) To work with video files, you need Photoshop to be in 32-bit mode. Right-click on the application and go to Get Info to get to that option.
2) The Get Info screen. Click on Open in 32-bit mode.
Cinemagraphs are in. If you haven't heard the term, a cinemagraph is a still photo that has some part of it animated. These images are meant for web display, and they're a great example of how digital means for displaying images are bringing new aesthetics and possibilities. A cinemagraph is different from a video clip in that only a portion of the frame is in motion, and often that motion is subtle. Think of a photo of a model wearing a long gown that's flowing in the wind. The windswept look in her hair and dress might convey the sense of motion, but by animating the dress itself, you've created something very different.
Cinemagraphs aren't difficult to make, but you should plan it out to make the best use of your valuable time. The cinemagraph starts with a video clip. Plan the clip such that you're able to isolate a moving element easily.
What's easily? That depends on your Photoshop skills and the amount of time you want to spend making layer masks. You want to shoot the clip with the camera locked down on a tripod. Anti-shake fixes in video-editing software like Adobe Premiere Pro and Apple Final Cut Pro can allow you to shoot the clip handheld, but if you work from a tripod, you'll save that editing step and you'll be assured of good results.
3) With Photoshop in 32-bit mode, go ahead and open your clip. If you're having trouble, make sure the clip is in a format that Photoshop can read like .mov. This is where you'll make your initial edit to get your clip to a manageable size for the cinemagraph.
4) To see the frames of the clip, you need to open the Animation Pane. Go to Window > Animation.