The parent division of the player that contains the "floatright" class is removed by a script. Strangely, this only happens on MediaWiki.org (any skin), but not on Wikipedia or Meta-Wiki.
Topic on Extension talk:TimedMediaHandler/VideoJS Player
These wikis run a different thumbnail layout (based on the figure element), that TMH isn't entirely ready for yet. This is a known issue and when the changed figure-based layout will eventually move forward to other wikis, then this will have to be fixed first yes. Thank you for paying attention.