The short answer is yes, but there are a few things to keep in mind. The "3D" effect is not a true 3D, but rather a simulated one. Video is actually easier to pull this off with than still images. When you make a true 3D image, you need to shoot it with two lenses that are placed a reasonable distance apart from each other to capture the image at slightly different angles. The two images are combined into a 3D video format (or still image) such as SBS (side by side), anaglyph and others. What these 2D to 3D video converters do is "fake" this shift between shots by combining the current frame with the previous frame at any given moment. The assumption is that there will be some movement between both frames and the combination of both frames will produce a three dimensional effect. In reality, it's not anywhere near as good as true 3D, the camera movements and camera position need to be just right relative to the subjects being shot for it to kind of look convincing.
A more advanced method, that will also work with static still images, is to create a depth map then use it to generate two iterations of the image with slight variances. The depth map looks like a black and white mask in Photoshop, but can be used to make a selection on the image and alter it to create two versions of it. This technique was also used, on a frame by frame basis believe it or not, to convert 1997's Titanic into 3D. This too, isn't 100% perfect, and it really depends on the quality of the depth map you create.
