Not easy to deal with technically challenged clients.

Regardless of how "easy" we think we have made a system work, it can still be confusing to some.

The DVD example above is a good one.
We try to make things neat and tidy buy putting things into racks or cupboards, and setting up remotes to do just about everything, and there still can be issues.

Equipment is all black, so seeing buttons to open / close can be hard, and forgetting that there is a button on the remote isn't unheard of if the client doesn't use the player often.
In fact that is one of the biggest issues we face as CI's, we install all this gear for people and in the end have no idea what actually gets used and how often.
Even devices that may get used daily, may not have all it's features used.
I was recently at an older clients home and he asked about recording on his cable box. (this system was installed about 4 years ago).
He had no idea how to do it, was not even aware that the standard symbols for play, stop, record etc on his remote had anything to do with using the cable box.
Now, I know we showed him when the system was installed, and he admitted we probably did. But, it was a feature he never used right away, so he forgot about it.
Because we do such a great job of making things easy to use, clients don't take ownership of their equipment. They don't read a manual, they don't try things.
How many clients have an Apple TV in their system and use it for anything more than renting movies / TV shows, their music and Netflix? Do they not wonder what is behind all those other icons on the screen?
Sorry, getting a bit off topic there.
Service contracts are all we have to protect us from working for free after the sale.
You need to figure out what works for your business model and clients.
After the system is installed you could offer up to "X" free site visits. You should also make sure you spell out how you deal with warranty work, as I have yet to hear of anyone getting paid from a manufacture to deal with their products when defective. (yes there are some that at least jump and help you get things back up and running quickly). Then offer your service contract, again spelled out so they know what to expect from you when they call.
One idea is to offer a contract that includes 1 or 2 site visits per year (great for vacation homes, you come in before they arrive and again when they shut it down for the season). These visits enable you to do a full system check up. This way you will have seen and confirmed everything in their systems are working as they should, and spot any issues as the system ages. You can update firmware / software and it also gives you the opportunity to discuss upgrades / new tech.
Along with this, would be to give clients that opt in for the service contract priority service or a slightly discounted rate for any other issues that could arise during the normal course of use.