You didn't include any RAM with the first build.
FIrst and foremost, you have to ask yourself "Are there real reasons why I specifically want OS X over Windows 7 or any other operating system?" If you cannot think of many specific and practical reasons, then you should probably avoid using OS X.
If you still want OS X for very specific software that you absolutely must have, you could always dual boot for all your other needs that require WIndows/Linux/BSD.
However, if you want to use OS X, you must ensure that there is proper driver support for every piece of hardware where drivers are relevant. Chipset, audio, video, USB, even specialized peripheral drivers if applicable (and if it matters to you). You may need to adjust your hardware for those purposes.
Speaking of which, why did you change some of the stuff between the two builds? The CPU for example. As far as I know the CPU makes no difference from one operating system to another, only the chipset does.
How intensive and frequent will your video editing work be? If this will be the primary focus of your computer, then you should invest a bit more for a 2TB HDD in the least, and increase that RAM to 16GB, the hard drive upgrade taking priority. Video files take a massive amount of space before being compressed and so on. Video editing is also one of the few things that will actually take advantage of that much RAM, so if your sessions are intensive you will benefit from it.
It also goes without saying, but a 128GB SSD for your OS and your main software would be beneficial. Also, if you have a large amount of money to spare, a larger SSD that is set to work as a cache for your HDD would be extremely useful to one such as yourself who will be opening very very large files likely many many times before being finished with them. However, I know little about using an SSD as a cache, so if it interests you, you will need to ask someone else for a proper explanation.
In summary, don't use OS X unless you have a valid reason for wanting to, or you may end up with more trouble than it's worth. Definitely upgrade to a 2TB HDD. You may also benefit from an upgrade to 16GB of RAM.