If you can’t play any audio or video, it’s because of a bug on the fwplayer_osx binary that occurs on older versions of MacOSX.
Here’s a build that addresses the issue while we release 5.5.1:
Download 5.5.0 hotfix release for MacOSX
http://dl.frostwire.com/frostwire/5-beta/frostwire-5.5.0.player_hotfix.dmg
5.5.1 will feature:
– A new setting so that you can use the system’s default player instead of the FrostWire player.
– A fix on the Torrent detail dialog where filtering is not working.
Official FrostWire Blog 