Could the guy be served a subpeona and be compelled to give up the footage?
Served, yes. Compelled, probably. Kentucky requires only the signature of a lawyer licensed by the state bar and known to the court to have a subpeona duces tecum* served. Or a citizen pro se can file and have the court clerk sign one to be served. Here's the short form:
Dude could then try to quash (latin for squash) the motion on technical grounds, but in the end I think it's likely he would be compelled, because he himself admits he has them. It would be like compelling his testimony if he was a known eye-witness to a crash.
On the other hand I agree with Ari that it would be worth something to not have to go the court to get access after a possibly lengthy delay. Furthermore the subpeona requires that you actually have filed a case, something you may not want to do until you have seen the footage. Also a non-party subpeona requires you to notify opposing counsel of your request, and then the court will also notify all parties if and when the subpoena materials arrive.
So there may be good reason that an insurance investigator would pay for private access to the footage. But isn't there still something morally remiss about doing nothing but waiting around for a pile-up, and the bigger the better? Even ambulance chasers have to chase, right?
If the guy really wants to make it tough on the subpoena process though, I would recommend setting the VMS system clock ahead 113 days, 7 hours and 33 minutes... and the time zone to Fiji, just to make it easy when he hands over the drive. ;)
*duces tecum is a latin term which can be loosely translated as take'um docs
All the above is IMHO since IANAL, and anyway I know you know this stuff already, Marty.