Jim,
I have been experiencing a very similar problem in Black Shark that I believe is the same issue (correct me if you're seeing something different, Moose!): when I try to playback tracks recorded from a multiplayer session, they "go bad" after a few minutes. By "go bad" I mean that playback shows events differently than they actually occurred. For example, in one particular session, I took off from a FARP, headed into enemy territory, took out two enemy AI COBRAs with Vikhrs, took out another one with the cannon, but took a beating from a 4th and had to limp home, making a miraculous emergency landing at base. When reviewing the replay, everything seems normal up to the point where I intercept the Cobras: then, according to the replay, I lazily hover while the Cobras proceed to nail me from my flank, destroying my poor Shark while I don't react at all. This most certainly didn't happen in the online session!
It *appears* as if the AI Cobras are behaving/reacting differently in the replay than they did in real-time, and, since the track is just playing back my recorded inputs, the mis-match destroys the accuracy of the playback, leading to the frustration that Moose expresses above.
This happens whether I'm hosting or joining another server. The only tracks I've checked have been very large, and I've always used time compression to get from the start of the track to the juicy bits and wonder if something's getting out-of-whack during the speeded up bits?
I'm playing Black Shark 1.0.2, patched over 1.0, no mods whatsoever.
Panzertard has a good description of the problem (and what seems like a reasonable suggestion for a fix) here:
http://forums.eagle.ru/showthread.php?t=42571