I used to do parking at every circuit assembly, and once I did it at a district assembly.
It was in the bottom half of the "enjoyable" scale for assembly / convention volunteer assignments. Mainly due to the weather (we somehow managed to get the circuit assemblies that fell on the coldest & snowiest days of the year). At the DC, it was the opposite problem - you'd be drenched in sweat by the end of the morning, then have to go into the air-conditioned facility and hope you didn't get pneumonia.
I can't for the life of me imagine why a training video would be needed. How long does it take to explain "wave and point, don't get run over, say 'watch your doors' and 'good morning brothers' as they park".