TV ads about Bitcoin could greatly induce the elderly into knowing more about it. However, such efforts could be in vain as most seniors aren't into the latest technological breakthroughs. All the "technical jargon" surrounding crypto/Blockchain tech, makes everything look complicated especially to non-tech savvy people. The elderly are better off using physical cash for daily payments, as it won't be going anywhere soon. It might take decades before the world's economy fully transitions into a cashless one. While we're in the "transition phase", physical cash will still be a relevant payment method. I'd expect the elderly choosing physical cash over Bitcoin because of its easier learning curve and price stability. Only a small minority will use Bitcoin as an alternative financial system for their own benefit.
All in all, young people will be the ones that will adopt Bitcoin to a full extent. It's evident that old people are reluctant to change. They're accustomed to the traditional way of making payments via the legacy financial system. While it's not that hard to make the elderly understand how Bitcoin works and how to use it, most of them will continue living with Fiat. There are many educational materials available on the web right now that you can use to carefully guide old people into the "crypto revolution". In all ends, the decision of joining Bitcoin will ultimately lie on the person himself. Just my opinion
That is actually a great idea BUT placing it on public advertisements means that it won't just be introduced to the elderly. It would also present Bitcoin as an usable Currency that people can gain money from. It would go through lots of processes before making it into an advertisement since networks won't advertise what they do not understand. It would still be a good idea to just show results and outputs from what can we benefit from Cryptocurrencies. In that way, people who are only interested would be entice to ask necessary questions.