"I am finding them before URLS e.g. privacIE:youtube.com."
I am not 100% sure I understand that, but--
The Content.IE5 folder is relatively hard to reach and open.  One way is to enter C:\Documents and Settings\UserName\Local Settings\Temporary Internet Files\Content.IE5 into the Address line of either IE or Windows Explorer.  
The Content.IE% folder contains an index.dat file which contain info about all the sites you have visited lately, including the URL's of those sites.  Clicking on this file accomplishes little.  You will not be able to read the URL's.
This folder grows and grow unless cleaned out.  They are not cleaned by using IE's own tools to delete Temporary Internet Files.  
So, to read the URL's in Content.IE5's index.dat file you need a reader
http://www.acesoft.net/index.dat%20viewer/index.dat_viewer.htm
http://support.it-mate.co.uk/?mode=Products&p=Index.datSuite 
There are several index.dat folders on the PC so you will want to be sure you are looking at the one in TIF.
You can also read these files by using http://www.nirsoft.net/utils/iehv.html
To clean out Content.IE5 you need a third party program.  
I use System Security Suite
http://www.geocities.com/igor_shpak/
Others use CCleaner
http://www.ccleaner.com/
And I think iehv.html will do it, too.
As I said at the beginning, I am not sure what you mean by "I am finding them before URLS e.g. privacIE:youtube.com"
If cleaning out Content.IE5's index.dat file has not fixed the problem, post back.

jdroger2--I made a slight misstatement in my last post.  
The Content.IE5 index.dat file contains the URL's.
However SystemSecuriitySuite and CCleaner clean out the whole Content.IE5 folder, not only the index.dat file.  That is good.

jdroger2--Just had an idea what "I am finding them before URLS e.g. privacIE:youtube.com"
might mean.  If you are running IE8's Inprivate mode, that is likely what you will see.
http://www.microsoft.com/windows/internet-explorer/features/safer.aspx
Click InPrivate on the left panel.

These are the results I have pulled from doing an investigation of the index.dat files using some 3rd party software that reads them.  I know how to read them and clear them out I am just trying to justify where these results are coming from.  I am not seeing this in history itself in IE.  

jdroger2--Well, as you said, these prefixes seem to be part of IE8.
And asI said, PrivacIE seems to be connected to IE8's InPrivate setting.
http://forum.servomagazine.com/viewtopic.php?f=2&t=13790
Though there also are references to it being a sign of malware.
incompat also figures in IE8
http://tetlaw.id.au/view/blog/which-urls-are-on-the-ie8-compatibility-view-list
I assume this is one way IE8 identifies that you visited a website while in InPrivate mode.
And are you sure you mean ieltd rather than ielts?
http://www.google.com/search?q=+ieltd+&rls=com.microsoft:en-us:IE-SearchBox&ie=UTF-8&oe=UTF-8&sourceid=ie7&rlz=1I7ADBF

"These are the results I have pulled from doing an investigation of the index.dat files using some 3rd party software that reads them. "
I presume that "3rd party software" is something like
"So, to read the URL's in Content.IE5's index.dat file you need a reader
http://www.acesoft.net/index.dat%20viewer/index.dat_viewer.htm
http://support.it-mate.co.uk/?mode=Products&p=Index.datSuite   "
to which I already referred you.


Sorry.  That is the best I can do for you.  I never said you would find the prefixes in History.

I have an index.dat reader that I use already. That is where I'm seeing these results.  So we are assuming these are traits of IE8 but have no definitive answers on any of them?

jdroger2--
I said (based on links provided) "PrivacIE seems to be connected to IE8's InPrivate setting.
" I assume this is one way IE8 identifies that you visited a website while in InPrivate mode."
I said "incompat also figures in IE8"
You said "So we are assuming these are traits of IE8..."
I asked if you are sure you meant "ieltd" rather than "ielts".   No response.

You said "...but have no definitive answers on any of them?"
As Bill Clinton said--It depends on what you mean by definitive.  
What would satisfy you?  Have you tried running NOT in InPrivacy and see what index.dat reports?

"PrivacIE seems to be connected to IE8's InPrivate setting.
" I assume this is one way IE8 identifies that you visited a website while in InPrivate mode." .. Fair enough I will test by pulling my own history and seeing what happens.


I said "incompat also figures in IE8"
You said "So we are assuming these are traits of IE8..."  Actually it is iEcompat ,, not incompat

I asked if you are sure you meant "ieltd" rather than "ielts".   No response. .. Yes I am 100% sure it says ieltd

I would be satisfied seeing some documentation from a reputable source such as Microsoft or a forensics investigator who has done the proper testing.

Thanks for your help.

Yea, you can never be too sure.  Thanks for your help jcimmaron.  Here is the post the answer from the xways forum here for anyone who needs it for future reference:

This is what I got from Microsoft.

The index.dat in the IECompatCache is a "Compatibility View List" of websites like iecompat:google.com. This list helps make websites designed for older browsers look better in Internet Explorer 8

The index.dat in the IETldCache contains a random selection of second level domains which were never visited.

The index.dat in the PrivacIE contains the privacy policies related to browsing.


All these are set by default when you first start IE8 and have to make some choices before IE8 starts

jdroger2--Thanks for the MS info.