Yes. Certs can expire after whatever time the issuer wants to set for them. That could be six months or 20 years. Some infrastructure has limits on max and min lengths (more max than min usually) but not all and there are best practices as well.

More importantly the certs could have been five years old by the time this person got the TV for a total age of 8 years.

Yeah until it starts hitting widespread hardware decode support (streaming devices and phones) it’s pretty much just a curiosity to all involved as the only things traditionally powerful enough to software decode these codecs at 4k without overheating are computers and I don’t see that changing.

If h266 gets hw decode support on a bunch of common chips first it’ll be a real blow licensing freedom or not.