Video training is becoming a very common way to learn these days. With Tekpub, Peepcode, Pluralsight, Code School, and many others, there are usually great productions to teach you any development topic that you'd want to learn about.
All of these services are great, however I'm becoming a fan of the smaller, more focused screencasts. Railscasts, for instance, has been instrumental to my Rails learning development. Destroy all Software teaches me new things every week.
Smaller videos like this are easier to digest, and are more focused on a single topic. Like the boiled frog you eventually realize how far you've come on a topic, simply by watching regular videos.
iOS Development is an ever-changing landscape, with so many topic areas to cover, that a single training class or screencast series just can't teach you all of it. Instead of trying to cover everything in depth (increasing the length of videos). I find it valuable to have smaller, focused tutorials that teach you one thing, and do it quickly and effectively.
NSScreencast will be launching soon and will feature regular bite-sized videos focused on a single topic related to Objective-C and building iOS applications.
NSScreencast will include free videos. Down the road, a nominal paid subsribtion will unlock access to more content.
I still have lots to do before I release the first video, but if you like the idea, please sign up on the site to be notified when it launches. Thanks!