I just don't see the LE being at any fault for the surveillance video delay. Measuring from the crime scene to the gas station in question, there are 100's of other businesses closer to the crime scene than this specific location. In addition, most of those other businesses are closer to route 95, which seems to carry more traffic for people going in, and out, of Moscow. I don't fault anyone on wanting to focus on prioritizing all of those locations over this gas station, and there just doesn't exist the manpower to get every piece of footage from an area with so many businesses in a dense location.
Good for the person at this gas station for taking the time to review the footage on their own and help out. That's what a good citizen does, and, instead of the people criticizing and saying, "Why didn't LE visit us earlier," maybe they should look at what the people did at this gas station and follow their example. They wouldn't even have to review it! Common sense would tell someone to hit save on those nights, and then send it over to the tip line.
I have cameras on my home, and I review things frequently when there are crimes even remotely close to my area. You just never know. A lesson to all to be proactive and helpful, because investigators can't be everywhere all at once.