Adding the following to
/usr/share/hal/fdi/information/10freedesktop/10-usb-music-players.fdi fixed it:

        <!-- TrekStor i.Beat jump MP3 Player -->
        <match key="@storage.physical_device:usb.vendor_id" int="0x066f">
          <match key="@storage.physical_device:usb.product_id" int="0x835d">
            <append key="info.capabilities"
type="strlist">portable_audio_player</append>
            <merge key="info.category" type="string">portable_audio_player</merge>
            <merge key="portable_audio_player.type" type="string">generic</merge>
            <merge key="portable_audio_player.access_method"
type="string">storage</merge>
            <merge key="portable_audio_player.storage_device"
type="copy_property">info.udi</merge>
            <append key="portable_audio_player.output_formats"
type="strlist">audio/mpeg</append>
            <append key="portable_audio_player.output_formats"
type="strlist">audio/x-ms-wma</append>
            <append key="portable_audio_player.input_formats"
type="strlist">audio/x-wav</append>
          </match>
        </match>

I didn't know if I should add wav to the output formats because the manual
states that the player can only play 8kHz and 16kHz wav files (the same formats
that it can record).