Using video in Processing is, sadly, really painful. You can do absolutely wonderful things once it’s working — pixel-by-pixel manipulations that are hard to do elsewhere, and easily-coded OpenGL manipulations that should help generate powerful eye candy. But the list of issues runs something like this:

• Windows doesn’t support capture without the addition of the buggy WinVDIG, which often doesn’t work properly.
• Linux doesn’t support anything.
• Capture is slow on Mac, and sometimes doesn’t work.
• QuickTime updates regularly hose the whole setup.
• Important QuickTime features aren’t supported.
• Playback is slow.
• Playback often crashes.
• Things just don’t work, and you don’t know why.

Now, granted, for simple sketches and experimentation, the library often will work. Or at least, it works except when it doesn’t — and you can read about how often it doesn’t in the reference.

Fortunately, I think the situation could be — and soon will be — very, very different.