Media sub-type tag getting dropped from metadata
Videos tagged with a "Media sub-type" are intermittently losing this attribute if the "File format" option is not also set.
Once files are tagged with HD, standard def, DVD etc - they never lose any Media sub-type info, however if this element is set set, the media Media sub-type is lost.
This has been observed in 0710 and 0810 Beta 2 (updates from 08/04/2010).