NV4 says 4.5 GB Temp Needed But Requires 9GB?

I upgraded to Nero 7 5.X recentley as I had tried Nero 7.0.8.2 in the past but had a problem that when I skipped through the video to make chapters in specific places, the video would freeze up and take several minuetes for the video to start playing again. I downgraded back to Nero 6.6.

Anyways with that said I am trying Nero 7.5 and am not sure if this is a bug in this version or a Nero 7 bug in general as it makes some sence.. but when burning a movie using Nero Vision it says I need (for example) 4.5 GB of free hard drive, which I have. However when I click burn to Hard Drive, it says I need 9 GB of HDD space in order to burn the procedure and once it is done the extra 4.5GB it required is then freed up.

I can see how this makes since as it needs 4.5 GB for the project and the other 4.5 for temp space for the encode, but I can't seem to recall this being the case in Nero 6.

Thanks for any responses, and my apoligies if I complicated that to much