Like Kamkar mentioned, reviewing the daily files to see what the driver is up to is going to be a pain.
I'll estimate 1-2 hours for each truck, per day, for somebody to scan through the files for an 8-10 hour period of recording.
I've been driving commercial trucks or buses for a total of 35 years.
If the vehicles are local, it's probably more productive to go out and spot check what the trucks are up to, than to record everything.
There's probably some inexpensive GPS tracking unit that would identify some problem people.
(Some of them may have a GF they like to visit for a few hours every work day, or some favorite place to stop to 'drink' a lunch.)
(I remember one guy who would park at a bar across the street from the truck terminal for a few hours as soon as he started work. All the drivers knew it, but it took the company a few hours to catch on, but they could probably look out of the office window and see the truck sitting there.)
You're still better off having a reliable dash cam to record accident/incident type stuff.
I run 48 states in the US, and have to deal with office types who don't understand that while yesterday I only drove maybe 200 miles, since I was in congested, risky streets and roads of the NE US, it took 8 hours to do it. Add in a delivery and a pick up, my work day was 12 hours. (I'm not paid by the hour) They probably assume I was screwing off. I wish I was!