The NTSB CVR folks have capability for sound signature analysis and may be able to extract useful data from the various doorbell cam audio files. Tail and rotor RPM shouldn't be too hard. A control malfunction may have a sound signature. Possibly rotor aspect can be determined from doorbell location and ADS-B position data. Raw ADS-B transmissions are good data, especially given the hoops that have to be jumped through to certify an installation.
Result being that a subset of data normally available from FDR and CVR exists, but has to be collected from disparate sources.