The summary says it all. Newer versions of both libebml and libmatroska have been available for a few weeks, and the latest VLC requires them, so it would be nice to get them updated in FC-4. I've tested the update, and it's just a matter of bumping the version.
No objections here if you've tested them and there's no soname changes etc. I also guess that Dams wouldn't mind you taking over maintainership of these two packages...?
Then I'll double check and go ahead and update them myself this time. Do let me know if you want to transfer the ownership, as I wouldn't mind, especially since I've got a few package depending on those.