I can only recommend what I have used for years;
It is relatively simple, available on the App Store and need not be the Pro version. Once you have converted one the process is the same for all. I think only the pro version can do "batch" conversions and it's not free but I can't remember the cost, I've had it since version 1.
How does he intend to replay them, that will decide what format to save them into?
The other aspect is storage, these saved movies can take up a lot of storage, the average 90min movie can run from 1-4GB depending on Definition.