The steps used to define a microformat may be put to use for defining a videoblog. One of the relevant steps is finding common usage on the internet (in the wild) to create a standard:
http://microformats.org/wiki/process#Propose_a_Microformat
Paraphrasing the page:
"...A pattern has emerged from successful microformat development
efforts of several specific kinds of wiki pages being created, in a
particular order (though not always)....
you think needs a microformat. Document them with URLs. Document the
implicit schemas that the content examples imply. This is the action
that helps follow principle 3, design for humans first, machines
second ... adapt to current behaviors and usage patterns. Start by
cloning the examples page and filling it out."
So real examples of the different videoblog types are listed here or on a related page from which common attributes are abstracted toward the definition.