Video length iPhone 4

There are a number of factors that affect the file size in a digital video. The amount of color changes being one, and the file compression algorithm is the biggest. Right now, there is no way to know the file size for the iPhone 4, since we can only guess at what the files sizes will be based on the 720p HD recording. I don't have a 3GS, so I cannot speak on that matter.

The last aspect that would affect how much video you can record is the amount of free space that you have left available on the iPhone. Maybe someone with a 3GS can come in here and let you know what kind of file sizes they have experienced, however that may not be a predictor for the iPhone 4.

I have recorded videos of more than an hour on my 3GS 16GB. Im not sure if there is a limit, other than the amount of free space on the hard drive. One problem with recording long videos that I have had was transferring the video to my computer afterwards. Ive had to break the video into smaller parts, which is very easy to do with the iphone software.