I've not heard of that limit. I've had clients importing 30 minute, 60 minute and longer video into Presenter (I wouldn't recommend it). I would be more concerned about if your video is not in FLV or MP4 format before importing it. Presenter can convert the video to FLV if it is not in one of those formats, but I've had very mixed results in that function. Using a video conversion tool will give you more control as to the quality of the output in the appropriate format.