Indeed, there used to be a lower priced still-capture-only version, which has long since been discontinued. As to capturing audio (as part of video), for that to work Ambrosia Audio Support needs to be installed. Unfortunately, the AAS installer fails* on Yosemite and according to some on earlier versions of Mac OS X as well (if true, I’m not sure where the problem started). This failure is likely due to the fact that Mac OS X audio handling has changed over time, and Snapz Pro hasn't kept up with those changes.
Likewise, to maintain basic compatibility with newer Mac OS X versions, Ambrosia's audio app Wiretap Studio too has lost features that reduce its utility. The general lack of full feature updates seems to be related to the rumor that Ambrosia is on life support. It’s suggested that there are no more employees other than founder Andrew Welch, and that he can only do so much.
*) The installer runs without problem, but it doesn’t have any effect: after the mandatory reboot Snapz Pro still complains about requiring AAS.
