Keylogger

[bst]

The cause for this alert is BS.Players global support for keyboard multimedia keys. BS.Player installs WH_SHELL hook to receive HSHELL_APPCOMMAND messages and detects when multimedia keys are pressed. ZoneAlarm detects this and shows security alert.

You can verify this if you uncheck 'Enable global support for multimedia keys' option and restart BS.Player. Now ZoneAlarm won't show any alerts. If you re-check this option warning will be shown again.
It's nothing to worry about. It's recommended to leave it enabled, so multimedia keys will work even if BS.Player window is not active (ie. in background).