These use cases assume Flash is disallowed. A compromise could be to say, accept Flash but only if it is playable with entirely libre software (e.g. Gnash plugged into GNU IceCat running on gNewsense).
Pros: Conversion of .flv to OGG formats WebM can be automated.
Cons: managing which .swf files are playable is time consuming and awkward. Converting to a format that is easy to edit seems difficult. Easier to disallow Flash.
Please discuss and advise.