Instruction: Generate an answer to the question by utilizing the information contained in the document.

Input:
Question: How much power and video cable length does the arm use? Need to figure out if I should order an extended power and vga cable.
Document: I knew I had wanted such a flexible arm and looked around for one with a through and through grommet compression mechanism. This turned out to be an extremely easy install and sturdier than I thought. The only unexpected outcome is I needed to order a longer video cable. No detrimental side effects
Because of the extra length this arm adds when extended, you may want to consider buying a longer monitor cable at the same time you buy the arm. Standard monitor cables are about 5-6' and unless your monitor is very close to your machine, a standard cable might be too short.If I haven't added an update to the top of this review, this product is still working out great for me.
My monitor is twenty-seven inches. So my choices were to either keep the arm as a decoration or figure out how to use it. Against my better judgment I took the advice I found while searching for a solution on the internet and purchased a small amount of industrial strength velcro. Much to my surprise, it works! Four strips of the velcro attached to the back of the monitor and to the mounting plate on the arm provide a four inch by four inch square of surprisingly strong adhesion.
Decided to buy the tall pole just in case I would ever need to be standing for whatever reason (Was only 10$ more and prime eligible). I bought this to use with my Wacom Cintiq 21ux as holding it in my lap for extended periods of time was wayyyyy to heavy. I'm an animator so sessions are very long when using my cintiq. Set up was a breeze!
This monitor arm is sturdy, solid, well-built, and looks good. The tall pole is great, gives me lots of options for positioning. The cable routing feature is pretty good, although I would have liked to see a recess on the upper arm like the one on the lower arm, instead of having to use cable ties. I deducted one star because I had a problem attaching my monitor.
This works for now when I adjust the height from the arm and *not* the monitor, but I am still going to need to add some more metal reinforcement so that someone unaware of this doesn't break the monitor's plastic backing. I am not comfortable with only two of the four mount points being used anyhow. I also wish that the clamp could have been extended an additional inch but I doubt that Ergotron's engineers predicted that their monitor arms would be used for this type of solution.
My monitor cord isn't long enough to reach the power outlet now. You could use an extension cord, but I chose to hang a power strip under the back of my desk (requires drilling two screws into the wood and hanging the power strip from them), so now I have one cord going to the outlet, and everything else plugging into a power strip out of sight but convenient to access.
This works well but the bolt is very long -- I'm not sure why they need a bolt that long. In my case, there was a drawer beneath the surface where I was mounting it and the excess length of the bolt interfered with the drawer.
This is a great monitor arm and exactly what I was looking for. It's steady strong and easy to put together. I have a lightweight 27&#34; Acer monitor, so don't worry about the size as much as the weight. The arm has a very broad base made of aluminum and there is no fear that will break or bend no matter how much I use it.
If you work on a computer for several hours a day, this product is worth every bit of currency you spend purchasing it.Only 4 stars, because there was no mention in the description that you might need to also order an adapter plate for your display.I mounted a Samsung 245BW display, which has a 200x100mm VESA mount.
Answer: The two pivoting part of the arm are about 1ft each, plus 1 ft fo the stand.   It is safe to assume it needs 3ft and then add extra length from where the base is from the power outlet for your power cable, and where your computer is from the base for the video cable.  I use 6ft dvi cables.