Is there a Zip file with green-frog.psd and red-frog.psd?

I didn't check the file links in the previous comments, but the frog is nothing more than a bunch of overlapping ellipses and circles and an upside down arc. It would not only be easier to create using a vector program like illustrator/inkscape, it would be more useful because you can easily change sizes and and colors later on. You are also not locked down to the image's pixels until the very last moment, when you want to insert it into your photoshop file.

Lowest level would be your background. I suggest transparent as that color can always be changed, even in photoshop.

Next level up would be an green ellipse [based on the video, under the frog's open mouth].

Next level up would be a second, larger ellipse, using the same color as the first one. This is the main part of the frog's head.

Next level up would be the green circles under the eyes attached to the head. Alternatively, you can build the the shape of the whole head in one step, similar to the profile of Mickey Mouse.

Next Level up. Create a medium-sized yellow circle [eye]. Duplicate it. Create a smaller black circle [iris]. Duplicate it. Create an even smaller dark green circle [nostril]. Duplicate it. Arrange these circles like they are in the video, either free hand or using alignment tools.

Next level up would be the mouth. You have many options on how to create this shape, but in keeping with the theme of using nothing but circles and ellipses, think crescent moon. By having two ellipses, one overlapping another and slightly offset, you can have the ellipse in the back creating the color, and the ellipse in the front simply cutting out the rest of the shape.

I don't think so there is any file to download. You can use stock photos.