Shooting a high quality video on iPhone 4s?

Is it possible to film high quality video on iPhone 4s? When I watch the video I filmed on iPhone, it seems pretty decent, but when I transfer that video on my laptop it becomes all grainy and awful. Is that an iPhone's problem or my laptop's? Any advice on how to transfer video from iphone to laptop so that it has good quality?

The 4s shot 1080p video which is for the most part the best standard today in video. Not sure as to why your videos end up as bad as you claim.

The problem is that the iPhone has a very small sensor which is about the size of your finger nail on your little finger. The pixels on this sensor are only 1.5 microns. The small pixels like those in the iPhone, or any smartphone for that matter, perform very poorly in all but the brightest of situations. The tonal range and dynamic range is the lowest you can buy. The small pixels also create a huge amount of diffraction which is the smearing of light.
To replace the camera module in an iPhone, it'll cost you $13 in parts off eBay. So do you really think a $13 camera and lens will have good image quality?

The iPhone will shoot reasonable quality video if you have enough light. Shooting in dimmer areas will pump up the ISO (sensor sensitivity) which makes the video noisy.

Watching the video on a small screen, like your phone, will make sub-par images look good. When you look on a large screen, all the deficiencies will become apparent.

I suspect that the way you are transferring your video is compressing it to create the quality problems. Use an app such as Transfer Pro which preserves the original file size and does not compress.

It's also possible that the program you're using to view the video on your laptop is compressing the file and causing the problem, especially if you are using an older laptop that doesn't have the speed to play a 1080p 30fps video. Try different programs/computers for playing the video.

The iPhone has a very small LCD screen. Gross flaws are naturally hidden. What you see in the laptop and especially on the TV is what your video truly looks like.

How to shoot a high quality video on an iPhone 4s? Ditch the phone and grab a camcorder.

A 3" inch screen will make even low-res video look OK. Put it on a larger screen and you see things.

First - clean the lens.

Second - get a clamp and a cheap tripod for your cell phone. Try taking stills and video this way, then transfer to your computer.