In Impress, when doing Insert/Movie and Sound.. the selector does not show .ogv files under All Movie and Sound files. As .ogv is the default file extension used by ffmpeg2theora - and Ogg Theora videos work vey well within Impress it would be helpful - and encouraging to people trying to do this for the first time - if they were recognised as available within the selector.
I submitted a patch: https://gerrit.libreoffice.org/3609
Samuel Mehrbrodt committed a patch related to this issue.
It has been pushed to "master":
fdo#56832 Explicitly mention Ogg Audio and Video
The patch should be included in the daily builds available at
http://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More
information about daily builds can be found at:
Affected users are encouraged to test the fix and report feedback.