Is there a plugin for Aloha Editor that would let the user add audio/video files, one like the Media plugin in TinyMCE?
I'm not aware of such a plugin (select & upload video/audio; provide UI for different settings; list available media files) for Aloha Editor.
It's possible to use media files within Aloha Editor -- there is an oEmbed* content handler available -- if you want to insert eg a youtube video you can copy & paste the URL into the editable and the link get replaced with an embedded video.
Images, Videos and Rich Media is possible from those sources: http://embed.ly/providers