Don't know what you mean by "unpackers are not fit for use" - obviously, no unpackers apply here, on a movie file.
Regarding the time... well, it is slower than I would expect, but there isn't much you can do about it, I'm afraid. The Quick Scan is meant for scanning of single files - that's where the name comes from. On the other hand, it uses the highest sensitivity possible (so it's not that "quick" from that point of view) - so the whole file is scanned, from the beginning to the end - and it takes a while.
You can check the Task Manager during the scan to see how much CPU it uses during the scan. If it's 100%, it means that it really takes that much time to process the data. If it uses less, it means that the hard disk is unable to supply the data fast enough - and the computer is waiting for the data to arrive.
