There is no timing information in the underlying VP8 bitstream, that
is provided by the WebM (matroska) container. As far as I know, all
the data contained in an SMTPE time code is present in the container,
though not in the same format. Maybe you can elaborate on your
application and we can give you more info.
WebM files use time expressed in nanoseconds, with a actual resolution
determined by the value of the TimecodeScale. Typically the scale is
1000000 (1M), meaning that the resolution is 1ms.
-Matt