I exported a 1hr 35min Camtasia Studio 8 project to a techsmith encoded AVI. This looks fine when I view it using WMP. However when I import into Premiere Pro CS6 (6.0.3) it comes up as only 2min 32secs. I then thought I'd used Adobe media encoder but again the file shows as 2mins 32secs.
I don't use Camtasia, but I did save some previous discussions
Techsmith codec http://forums.adobe.com/message/3692768