sure 1080i uses the resolution of 1920x1280 if I'm not mistaking.
in addition 1080i is an interlaced format which means that on the first pass even rows of pixels are drawn and on the second the odd rows are drawn so on for each frame.
I'm a little confused by what you mean on how to work 1080i, it is a HDTV standard that can be seen on TVs that support the 1080i standard provided they are recieving a 1080i signal.
mind you that download is a 1080p which means it's progressive, it's the same resolution (so the pictures will be roughly the same) but every row is drawn every pass which they did because computer video compressions don't really support interlaced video.
oh and running a 1080p image is quite intensive on the computer.