Vendors of appliances containing Linux would love this technology. Think not only video recorders, also home network routers, firewalls, any set-top box, etc. As usual this will not only protect the device owner against evil attackers, but also the vendor against "attacks" from the device owner.
This is done currently for some devices, but because it is quite a technical feat, only happens for the things sold in big numbers. For these jailbreaking is worth the effort. A fear that this becoming Linux mainstream means that every mom&pop appliance based on Linux will use the technology. Jailbreaking every one of them is a big hassle -- c.f. the efforts spent on patching DVD readers to be region-free.
I think the only acceptable use of this is if buying a device means you get the device key shipped as well.