I agree that this looks like a nice tool, but as Ugh said, you'll most likely want a nice chunk of RAM available so that you can record at the resolution that you normally would any other day of the week. High-def resolutions like 720 and 1080 are standard for broadcast on YouTube and other streaming sites these day, not to mention, monitors that are capable of resolutions greater than 1920x1080 are becoming much more accessible to the public both in price and availability. A video with a resolution of 420x270 is just above the bare minimum of what YouTube will accept (240p) and that's not going to cut it when using fullscreen mode and it's stretched across a 1080, 1200, 1440, or 1600 display -- I can't imagine anyone would want to watch a video in that resolution, let alone understand what is happening in a video at that resolution.

I will also agree that it isn't always feasible to plan ahead and record endless hours of footage and hope you get something good (because it sucks to sift through it all afterwards), but 30 seconds is rarely enough time. It might be enough time in a game like a first person shooter where you can quickly get a fancy trick shot off or something like that, but let's say you're multiboxing on a PvP server and a semi-large battle happens to break out and drag on for a bit, you're most likely going to want more than 30 seconds available to you; but you could also argue that anyone running this program should already have their main capture program like FRAPS or whatever running in the background ready to pick up the slack of recording when the time is right.

TL;DR - I'd recommend lots of RAM when using a program like this so that you can record at mainstream high-def resolutions for at least a minute or two.