I am going to take a stab at this and this is only a guess on my part as I do not have enough information to know for sure what the problem is. I am also assuming that all other 120 volt electrical appliances are working when the generator is running.
I am going to assume that you own a Motorhome and that the VCR is plugged into the same electrical circuit as the front TV in your Motorhome. On some Motorhomes depending on the location of the front TV there is a safety system in place that prevents the front TV from receiving power when the Motorhome is in gear or if the generator is running.
This safeguard is in place to prevent the driver of the Motorhome from watching TV while going down the road. If you think texting is distracting while driving, try watching Dancing With The Stars while going down the road.
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