IMHO, I cannot for the life of me understand why video (for the purpose of incident investigation) is not on all commercial aircrafts.
In lack of better, ANY video system is better than none.
Pilot privacy, fear of enforcement action (FAA & law enforcement), and possibility of damaging evidence in civil lawsuits in case of a mishaps.
Little remembered now, but before voice recorders were mandated in cockpits, there was a huge backlash from pilot unions. Concessions were made and early CVRs were limited to 30 minutes (now expanded to 2 hours), no recordings can be made public (only transcripts), only NTSB investigators may access the recordings, and pilots can erase recordings once back on the ground.
The NTSB, UK AAIB, French BEA, etc., have all called for cockpit video or image recorders to be made mandatory for commercial flights, but given very strong union opposition I doubt it will happen anytime soon.