types for direct assignment to media elements

When we add direct assignment to media elements to the MediaCapture spec, do we want to allow things other than MediaStreams to be assigned? (Blobs would be a candidate.)   If we want to allow other  types, do we have a specific list that we want to allow?

If we do this, what should  the IDL look like?  Do we have to define exactly how direct assignment works for each type?  I don't have any opinion on the technical merits, but I'm afraid that spec-ing out "direct assignment  via MediaStream and maybe a bunch of other stuff" could turn into a bit of  a swamp.   Can we restrict the MediaCapture spec to MediaStream and let direct assignment with other types be speced elsewhere?


-          Jim