Putting iTunes on Windows was one of Apple's worst ideas. Windows was not designed to have iTunes on it. Now think about that for a moment. I said Windows was not designed to have iTunes on it. It means that Windows doesn't have the proprietary linkage it needs in Windows in order to function well. While this allowed most Windows users to use iTunes at a decent level, Windows users don't understand the concept of iTunes and will reject it because it's not like anything on Windows. It's not that Apple is making it tough for users to consume content, it's the people pirating and downloading non-compatible content to be run on Apple devices. If you download all content from iTunes, you would have a seamless experience consuming everything it has to offer. It's not that it holds the hardware back (unless you're using the Windows version), it's just that it optimizes the entire experience from start to finish from iTunes to your device. The main problem is your hardware and OS isn't designed to do the job it was supposed to do under iTunes if you're using Windows.
If you have existing content that you want in iTunes, you'll have to convert it to be optimal for iTunes because iTunes won't do that for you. It isn't a magical gold machine that keeps printing dollar bills, it's a piece of software designed to connect iDevices to your computer. Regarding video from a Canon DSLR, you can import directly to the iPad via the camera connector. If you wanted the movie on your computer, you just connect your camera to the computer. Not that hard.
So again, regarding video, audio, books, apps, and tv shows, if you're not savvy enough to convert the formats and understand the tech that works behind them, you should just purchase from the iTunes store because it just works. Don't put your foot in the blender and it will be all good. I'm on a roll with the kitchen references for some reason...