Blackmagic Intensity Pro works with uncompressed SD or HD video, and compressed codecs such as ProRes, DVCPRO HD, DVCPRO 50, JPEG, HDV and DV. It supports AVI and QuickTime files.

You won't be able to use video codecs like ProRes in iMovie, but you shouldn't have any problems with HDV and uncompressed video.

Blackmagic suggests to use Adobe Premiere Pro and Apple Final Cut Pro for maximum real time effect and full support of AVI and QuickTime files.