This is the incident: http://www.lasvegassun.com/news/2010/sep/23/officer-deadly-shooting-says-man-pointed-gun-didnt/
I couldn’t find an article detailing the missing video — but it disappeared/”was unrecoverable” from the lab they sent it to.
Generally those types of forensic recovering situations are sent to an outside lab because most agencies do not have the resources to extract the information.
The labs are under contract and usually do that type of work for more than one agency and numerous companies.
Some Honeywell engineers were always good for deleting files they needed. The hard drives would be removed from the machine and sent to Florida for recovery.