I would like to thank everyone who has responded to my questions and wanted to give an update on the "solution" I am about to pursue. After a lengthy discussion with a technician at the Other World Computing web site, I am beginning to believe that the issue has to do with the video card I have in my Mac Pro. Let me explain what brought me to this conclusion.
As I have explained before, when I imported the video material from the Phantom 3 Professional quadcopter, I was disappointed in its "jerky" appearance. After a lot of attempts to deal with this, I decided to see if I saw the same thing on other devices. So I viewed this on my iPhone 6 Plus, my wife's iPad mini, and her Macbook laptop. In all cases the video material was dramatically smoother in appearance.
I checked her laptop specs and saw that her RAM was less and the CPU speed was comparable. But the video card appeared to have more capacity. This brought me to a web search on video cards and I noticed that several reviews all mentioned Other World Computing as a good source. I reviewed their products that matched my Mac Pro and then got involved with an online "chat" with one of their technicians.
After reviewing everything that has happened, he suggested that it was not limited RAM causing this issue but more likely the video card. My current video card is an ATI Radeon HD 5870. The technician recommended a Sapphire HD 7950 Mac Edition. So, I am about to order this video card and we'll see how it goes.
Had I not seen such dramatic improvement in the video material on other devices, I might have just tried to increase RAM. Anyway, that's where things stand. I would like to also comment on the Codec suggestion. This is something I would likely pursue if the video card attempt fails. I'll try to get back after I take the next step. I have not converted from one codec to another but that is a hill I will certainly be willing to climb.
Again, thanks to everyone for taking time on this subject. It was truly appreciated.