I stumbled across this old thread today seeking an answer to another question.
When recording in bvr format and direct-to-disc, my current "work around" for capturing user-defined overlay text data that is relevant to an alert event is to check the 'Store alerts as high res files' control on the 'Camera Properties | Record' tab.
Whenever I need to inspect the overlay text that was relevant at the time of a particular alert, I simply open its high-res image (usually located in the 'Clips and archiving' Alerts folder).
To avoid unnecessarily capturing too many 'high res' images, I've been experimenting with using cloned cameras with more restrictive trigger definitions.
Perhaps there is finally a good reason to 'Store alerts as high res files'.