How to create .iso?

handbrake rips then converts into a playable format.
it does the extra step that mactheripper doesn't

On a Mac, you'll probably want an .img or .dmg file, as opposed to a .iso.

You need a program to take the ripped movie, compress it, then make a disc image. DVD2OneX does both those steps. It's worth the money. Use Mactheripper to rip the movie to your hard drive, then d2ox to compress it and save it as a .img file (or maybe it does .dmg). Then, whenever you want to burn it to a DVD, just use Disk Utility.

I agree with Dimwit, Mactheripper to DVD2OneX is a great combo. But just as a side note, you can watch the DVD after ripped by mactheripper just "as is". It'll rip the video_TS and audio_TS folders which you can play in apple DVD. Only downside is the file will most likely be huge (like 8 gigs depending on dvd). That's where DVD2OneX comes in, to compress it to fit on 4.7 gig DVDs.

I also use Mactheripper and DVD2OneX - they work great!