The incident was so far in the past that apparently someone going to the court house without knowing about it probably would have come up empty. The theory that was advanced is that the DUI was in the FBI file on George H. W. Bush (since that would include information on family members) and that that file had been one of those Hillary borrowed when they first went to the White House. That tidbit could then have been passed on to the operative who went to the court house and was able to find the file on the case (from 1976, I think)...which they then sat on until the Thursday before the election so that it would have maximum impact.
I was not a member of FR when that October surprise was pulled against Bush. At the time, I was working on Bush’s campaign and actively involved with the local Republican party. When Gore would not accept the results of the election, we (husband, son, and I) made signs and showed up for the protests in Sacramento. Around that time, my husband found out about FR and told me about it. I joined shortly after (hubby has never joined, but then he doesn’t make a hobby of posting anywhere). I actually found pics of the Sacto rallies on FR, with me and my son in them. :)