There are many ways to increase the resolution of a video. The most obvious of which is stretching, which just enlarges individual pixels, making them blocky. Most likely, any graphics hardware that you do have has support for scaling. This generally doesn't help much as general scaling makes your picture look like shit.
Scaling is not like in the movies where some guy gets a picture and clicks "enhance" and magically, you can see everything clearly. But there are definitely ways to scale up images.
If you go on wikipedia and look up "pixel art scaling algorithms" you'll find a whole bunch of ways to scale your picture properly.
The first image has been scaled well: by hq3x interpolation. The second image has been up sized 3 times without hardware support. (ripped from wikipedia)
If you use the hq4x algorithm to scale images, the result will be a picture with resolution higher than 1080p. hq4x can be done real-time, so there's no real point downloading a video with hq4x scaling.
You cannot enlarge photographs with this method unless you use color quantization first. Therefore reducing the quality of you photograph anyway.
This only applies to raster graphics. Anything vector can be scaled up without any problems infinitely. Therefore any 3d game can be rendered in HD. In addition to that sal or hqnx filters can be applied to textures in 3d games to create even higher quality. Rice's video plugin has support for high resolution textures also, so if you need better quality, you can always seek third-party textures to replace the original ones. An excellent example is the Banjo Kazooie texture pack, which includes Photorealistic textures.
One last technique which is generally used to enhance the quality of photographs is vectorization, in which a raster image is converted into vector through the use of tracing and quantization. This process is generally very processor intensive and only works when you want your photograph to look like a cartoon. I cannot see how an entire movie would be vectorized as there are so many easier options.
vectorized image
Raster image
The images are fairly large, so I won't display them on the page.
Also can someone, if they have the privelages, enable the <IMG> tags?