I am using Music Player Daemon, and I use the following script to turn gPodder into a client. My music is in ~/Music and I put the podcasts in ~/Music/Podcasts. The script works for both streaming or downloaded podcasts.

[~]$ cat bin/mpcut.sh
#!/bin/bash
if [ "$(echo "$1" | cut -b-4)" = "http" ]; then
    /usr/bin/mpc pause
    /usr/bin/mpc insert "$1"
    /usr/bin/mpc toggle
    /usr/bin/notify-send -i gpodder "$1 inserted to next spot in playlist."
else
    /usr/bin/mpc pause
    /usr/bin/mpc add "Podcasts/$(echo "$1" | cut -d"/" -f6-)"
    /usr/bin/mpc toggle
    /usr/bin/notify-send -i gpodder "$(echo "$1" | cut -d"/" -f7-)" "added to end of playlist."
fi

Audio Player in gPodder preferences is set to this: /home/christopher/bin/mpcut.sh %F

I have an application shortcut Super-G set to this in xfce4-keyboard-settings: env GTK_THEME=Adwaita-dark GPODDER_HOME=/home/christopher/.config/gPodder/ GPODDER_DOWNLOAD_DIR=/home/christopher/Music/Podcasts/ /usr/bin/gpodder

or you could use an alias: alias gpodder='GTK_THEME=Adwaita-dark GPODDER_HOME=/home/christopher/.config/gPodder/ GPODDER_DOWNLOAD_DIR=/home/christopher/Music/Podcasts/ /usr/bin/gpodder --verbose'