I think youtube aikido videos are great. I'd never have the patience to watch a Tissier DVD (but I go to his seminars and have some of his books), but having a 5 minute clip on, for example, tsuki irimi nage is very nice, especially when watching them at work between two tasks.
The great think is the search function. You want to know how to do ushiro otoshi ukemi? Youtube offers a tutorial. I still cannot do it and didn't expect to learn it just watching a video...but at least I know how it looks when someone can do it
Maybe it's not so great for details, but then - there are classes where you can learn the details,