Hard Drive space dwindling with Dazzle use?

[gnc115]

I bought the Pinnacle Dazzle video recorder for mac and have been using it to record some games off my xbox 360 for some fun. Each clip gets put into my itunes library under 'movies' and from there I drag and drop them into my external hard drive's folder, then delete them off itunes. Those clips move into the trash and I empty that, but for some reason my total memory continues to decrease. I have searched everywhere on my laptop for any traces of the clips but they are nowhere to be found, and so far I have lost about 8 gigabytes worth of space. Any help with this would be very much appreciated - (I don't want to continue using this product if it's going to mysteriously drain all of my memory).