This HTTP Capture function was built into the Gomez Recorder prior to the setup of Flash Ineraction. What this function does is create static requests for any objects generated through a particular plug-in on the page like Flash or Silverlight. If a flash object on the page generates certain images or objects, this function will manually call those objects to be downloaded.
However, when Flash interaction is enabled, this function becomes redundant and the customer may see duplicates of the same objects in their results. This is why this function is set to "off" by default. The only time one would essentially need to use this would be if for some reason flash interaction was not working properly and some objects needed to be called manually.