- Dropbox isn't great because (as far as I know) you don't get to leave messages as you do with Git/SVN commits.
- Git isn't great because (as far as I know) it's not so easy to quickly compare a whole history of iterations
- I haven't looked at hosted options for a few months, but they've always seemed to be expensive.
So you're left with:
- Trying to remember to incrementally increase filenames (Website01.psd, Website02.psd etc) - still leaving out memorable 'commit messages'.
- Saving the files with memorable 'commit messages' in the filename (Website_WideSidebar.psd, Website_NarrowSidebar.psd). Janky.
- Grouping all of your layers and duplicating the entire site for different iterations, turning on and off those groups to see previous work. Or using Layer Comps. Still janky.
- What I do in Illustrator (infinite canvas makes it easier than in Photoshop) - duplicating the artboard for each iteration, leaving a 'post-it note' to myself on the corner of each iteration. So I get the 'commit messages' and the ability quickly see all iterations at once. A recent example: http://c.jongold.in/1z452Y402o3V3s2d0r2W
I'd agree with the previous criticism about the video being too long - I'm sure you're aware of that though.
The pressing issue in versioning for me is being able to leave and view 'commit messages'/comments as simply as I can with Git - they're more meaningful to me that viewing solely by date. If you add that I think you'll have a great product.