adding support for "play with..." extension

adding support for "play with..." extension. It uses a clever hack, so it doesn't need an external application in order to launch mpv.

Also trimmed ff2mpv comment block.
and added .cache/youtube-dl

etc/profile-a-l/firefox-common-addons.profile

@@ -3,11 +3,15 @@
 include firefox-common-addons.local
 
 ignore include whitelist-runuser-common.inc
+ignore private-cache
 
+noblacklist ${HOME}/.cache/youtube-dl
 noblacklist ${HOME}/.config/kgetrc
+noblacklist ${HOME}/.config/mpv
 noblacklist ${HOME}/.config/okularpartrc
 noblacklist ${HOME}/.config/okularrc
 noblacklist ${HOME}/.config/qpdfview
+noblacklist ${HOME}/.config/youtube-dl
 noblacklist ${HOME}/.kde/share/apps/kget
 noblacklist ${HOME}/.kde/share/apps/okular
 noblacklist ${HOME}/.kde/share/config/kgetrc
@@ -22,15 +26,19 @@ noblacklist ${HOME}/.local/share/kget
 noblacklist ${HOME}/.local/share/kxmlgui5/okular
 noblacklist ${HOME}/.local/share/okular
 noblacklist ${HOME}/.local/share/qpdfview
+noblacklist ${HOME}/.netrc
 
 whitelist ${HOME}/.cache/gnome-mplayer/plugin
+whitelist ${HOME}/.cache/youtube-dl/youtube-sigfuncs
 whitelist ${HOME}/.config/gnome-mplayer
 whitelist ${HOME}/.config/kgetrc
+whitelist ${HOME}/.config/mpv
 whitelist ${HOME}/.config/okularpartrc
 whitelist ${HOME}/.config/okularrc
 whitelist ${HOME}/.config/pipelight-silverlight5.1
 whitelist ${HOME}/.config/pipelight-widevine
 whitelist ${HOME}/.config/qpdfview
+whitelist ${HOME}/.config/youtube-dl
 whitelist ${HOME}/.kde/share/apps/kget
 whitelist ${HOME}/.kde/share/apps/okular
 whitelist ${HOME}/.kde/share/config/kgetrc
@@ -48,6 +56,7 @@ whitelist ${HOME}/.local/share/kxmlgui5/okular
 whitelist ${HOME}/.local/share/okular
 whitelist ${HOME}/.local/share/qpdfview
 whitelist ${HOME}/.local/share/tridactyl
+whitelist ${HOME}/.netrc
 whitelist ${HOME}/.pentadactyl
 whitelist ${HOME}/.pentadactylrc
 whitelist ${HOME}/.tridactylrc
@@ -57,6 +66,9 @@ whitelist ${HOME}/.wine-pipelight
 whitelist ${HOME}/.wine-pipelight64
 whitelist ${HOME}/.zotero
 whitelist ${HOME}/dwhelper
+whitelist /usr/share/lua
+whitelist /usr/share/lua*
+whitelist /usr/share/vulkan
 
 # GNOME Shell integration (chrome-gnome-shell) needs dbus and python
 noblacklist ${HOME}/.local/share/gnome-shell
@@ -75,17 +87,5 @@ include allow-python3.inc
 
 # ff2mpv
 #ignore noexec ${HOME}
-#noblacklist ${HOME}/.config/mpv
-#noblacklist ${HOME}/.config/youtube-dl
-#noblacklist ${HOME}/.netrc
 #include allow-lua.inc
-#include allow-python3.inc
-#mkdir ${HOME}/.config/mpv
-#mkdir ${HOME}/.config/youtube-dl
-#whitelist ${HOME}/.config/mpv
-#whitelist ${HOME}/.config/youtube-dl
-#whitelist ${HOME}/.netrc
-#whitelist /usr/share/lua
-#whitelist /usr/share/lua*
-#whitelist /usr/share/vulkan
 #private-bin env,mpv,python3*,waf,youtube-dl